diff --git a/src/cmd/ksh93/tests/basic.sh b/src/cmd/ksh93/tests/basic.sh
index 33b8d64f5..b73ec9474 100755
--- a/src/cmd/ksh93/tests/basic.sh
+++ b/src/cmd/ksh93/tests/basic.sh
@@ -38,6 +38,13 @@ tmp=$(
 trap 'cd / && rm -rf "$tmp"' EXIT
 bincat=$(whence -p cat)
 binecho=$(whence -p echo)
+# make an external 'sleep' command that supports fractional seconds
+binsleep=$tmp/.sleep.sh  # hide to exclude from simple wildcard expansion
+cat >"$binsleep" <<EOF
+#!$SHELL
+sleep "\$@"
+EOF
+chmod +x "$binsleep"
 
 # test basic file operations like redirection, pipes, file expansion
 set -- \
@@ -146,7 +153,7 @@ cd ../../tmp || err_exit "cd ../../tmp failed"
 if	[[ $PWD != /tmp ]]
 then	err_exit 'cd ../../tmp is not /tmp'
 fi
-( sleep 2; cat <<!
+( sleep .2; cat <<!
 foobar
 !
 ) | cat > $tmp/foobar &
@@ -294,7 +301,7 @@ if	[[ $(for i in foo bar
 then	err_exit 'for loop subshell optimizer bug'
 fi
 unset a1
-optbug()
+function optbug
 {
 	set -A a1  foo bar bam
 	integer i
@@ -307,15 +314,15 @@ optbug()
 	done
 	return 1
 }
-optbug ||  err_exit 'array size optimzation bug'
+optbug ||  err_exit 'array size optimization bug'
 wait # not running --pipefail which would interfere with subsequent tests
 : $(jobs -p) # required to clear jobs for next jobs -p (interactive side effect)
-sleep 20 &
+sleep 2 &
 pids=$!
 if	[[ $(jobs -p) != $! ]]
 then	err_exit 'jobs -p not reporting a background job'
 fi
-sleep 20 &
+sleep 2 &
 pids="$pids $!"
 foo()
 {
@@ -325,8 +332,8 @@ foo()
 foo
 kill $pids
 
-[[ $( (trap 'print alarm' ALRM; sleep 4) & sleep 2; kill -ALRM $!; sleep 2; wait) == alarm ]] || err_exit 'ALRM signal not working'
-[[ $($SHELL -c 'trap "" HUP; $SHELL -c "(sleep 2;kill -HUP $$)& sleep 4;print done"') != done ]] && err_exit 'ignored traps not being ignored'
+[[ $( (trap 'print alarm' ALRM; sleep .4) & sleep .2; kill -ALRM $!; sleep .2; wait) == alarm ]] || err_exit 'ALRM signal not working'
+[[ $($SHELL -c 'trap "" HUP; $SHELL -c "(sleep .2;kill -HUP $$)& sleep .4;print done"') != done ]] && err_exit 'ignored traps not being ignored'
 [[ $($SHELL -c 'o=foobar; for x in foo bar; do (o=save);print $o;done' 2> /dev/null ) == $'foobar\nfoobar' ]] || err_exit 'for loop optimization subshell bug'
 command exec 3<> /dev/null
 if	cat /dev/fd/3 >/dev/null 2>&1  || whence mkfifo > /dev/null
@@ -372,9 +379,9 @@ chmod +x $tmp/scriptx
 cat > $tmp/scriptx <<- \EOF
 	myfilter() { x=$(print ok | cat); print  -r -- $SECONDS;}
 	set -o pipefail
-	sleep 3 | myfilter
+	sleep .3 | myfilter
 EOF
-(( $($SHELL $tmp/scriptx) > 2.0 )) && err_exit 'command substitution causes pipefail option to hang'
+(( $($SHELL $tmp/scriptx) > .2 )) && err_exit 'command substitution causes pipefail option to hang'
 exec 3<&-
 ( typeset -r foo=bar) 2> /dev/null || err_exit 'readonly variables set in a subshell cannot unset'
 $SHELL -c 'x=${ print hello;}; [[ $x == hello ]]' 2> /dev/null || err_exit '${ command;} not supported'
@@ -418,7 +425,7 @@ unset foo
 unset foo
 foo=$(false) > /dev/null && err_exit 'failed command substitution with redirection not returning false'
 expected=foreback
-got=$(print -n fore; (sleep 2;print back)&)
+got=$(print -n fore; (sleep .2;print back)&)
 [[ $got == $expected ]] || err_exit "command substitution background process output error -- got '$got', expected '$expected'"
 
 binfalse=$(whence -p false)
@@ -430,19 +437,20 @@ done
 if	env x-a=y >/dev/null 2>&1
 then	[[ $(env 'x-a=y'  $SHELL -c 'env | grep x-a') == *x-a=y* ]] || err_exit 'invalid environment variables not preserved'
 fi
+
 float s=SECONDS
-sleep=$(whence -p sleep)
-for i in 1 2
+for i in .1 .2
 do      print $i
-done | while read sec; do ( $sleep $sec; $sleep $sec) done
-(( (SECONDS-s)  < 4)) && err_exit '"command | while read...done" finishing too fast'
+done | while read sec; do ( "$binsleep" "$sec"; "$binsleep" "$sec") done
+((  (SECONDS-s) < .4)) && err_exit '"command | while read...done" finishing too fast'
 s=SECONDS
 set -o pipefail
 for ((i=0; i < 30; i++))
 do	print hello 2>/dev/null
-	sleep .1
-done |  $sleep 1
-(( (SECONDS-s) < 2 )) || err_exit 'early termination not causing broken pipe'
+	sleep .01
+done |  "$binsleep" .1
+(( (SECONDS-s) < .2 )) || err_exit 'early termination not causing broken pipe'
+
 [[ $({ trap 'print trap' 0; print -n | $(whence -p cat); } & wait $!) == trap ]] || err_exit 'trap on exit not getting triggered'
 var=$({ trap 'print trap' ERR; print -n | $binfalse; } & wait $!)
 [[ $var == trap ]] || err_exit 'trap on ERR not getting triggered'
@@ -479,28 +487,28 @@ set -o pipefail
 float start=$SECONDS end 
 for ((i=0; i < 2; i++))
 do	print foo 2>/dev/null
-	sleep 1.5
+	sleep .15
 done | { read; $bintrue; end=$SECONDS ;}
-(( (SECONDS-start) < 1 )) && err_exit "pipefail not waiting for pipe to finish"
+(( (SECONDS-start) < .1 )) && err_exit "pipefail not waiting for pipe to finish"
 set +o pipefail
-(( (SECONDS-end) > 2 )) &&  err_exit "pipefail causing $bintrue to wait for other end of pipe"
+(( (SECONDS-end) > .2 )) &&  err_exit "pipefail causing $bintrue to wait for other end of pipe"
 
 
 { env A__z=C+SHLVL $SHELL -c : ;} 2> /dev/null || err_exit "SHLVL with wrong attribute fails"
 
 if [[ $bintrue ]]
 then	float t0=SECONDS
-	{ time sleep 1.5 | $bintrue ;} 2> /dev/null
-	(( (SECONDS-t0) < 1 )) && err_exit 'time not waiting for pipeline to complete' 
+	{ time sleep .15 | $bintrue ;} 2> /dev/null
+	(( (SECONDS-t0) < .1 )) && err_exit 'time not waiting for pipeline to complete'
 fi
 
 cat > $tmp/foo.sh <<- \EOF
 	eval "cat > /dev/null  < /dev/null"
-	sleep 1
+	sleep .1
 EOF
 float sec=SECONDS
 . $tmp/foo.sh  | cat > /dev/null
-(( (SECONDS-sec) < .7 ))  && err_exit '. script does not restore output redirection with eval'
+(( (SECONDS-sec) < .07 ))  && err_exit '. script does not restore output redirection with eval'
 
 file=$tmp/foobar
 builtin cat
diff --git a/src/cmd/ksh93/tests/bracket.sh b/src/cmd/ksh93/tests/bracket.sh
index ff1f331d4..46238036c 100755
--- a/src/cmd/ksh93/tests/bracket.sh
+++ b/src/cmd/ksh93/tests/bracket.sh
@@ -130,7 +130,7 @@ fi
 if	[[ ! -w /dev/fd/2 ]]
 then	err_exit "/dev/fd/2 not open for writing"
 fi
-sleep 1
+sleep .01
 > $newer_file
 if	[[ ! $file -ot $newer_file ]]
 then	err_exit "$file should be older than $newer_file"
@@ -235,10 +235,10 @@ done
 rm -rf $file
 {
 [[ -N $file ]] && err_exit 'test -N $tmp/*: st_mtime>st_atime after creat'
-sleep 2
+sleep .02
 print 'hello world'
 [[ -N $file ]] || err_exit 'test -N $tmp/*: st_mtime<=st_atime after write'
-sleep 2
+sleep .02
 read
 [[ -N $file ]] && err_exit 'test -N $tmp/*: st_mtime>st_atime after read'
 } > $file < $file
diff --git a/src/cmd/ksh93/tests/builtins.sh b/src/cmd/ksh93/tests/builtins.sh
index a8fe9dd66..2f43aab5f 100755
--- a/src/cmd/ksh93/tests/builtins.sh
+++ b/src/cmd/ksh93/tests/builtins.sh
@@ -385,7 +385,7 @@ do	arg=$1 val=$2 code=$3
 	shift 3
 	for fmt in '%d' '%g'
 	do	out=$(printf "$fmt" "$arg" 2>/dev/null)
-		err=$(printf "$fmt" "$arg" 2>&1 >/dev/null)
+		err=$(set +x; printf "$fmt" "$arg" 2>&1 >/dev/null)
 		printf "$fmt" "$arg" >/dev/null 2>&1
 		ret=$?
 		[[ $out == $val ]] || err_exit "printf $fmt $arg failed -- expected '$val', got '$out'"
diff --git a/src/cmd/ksh93/tests/coprocess.sh b/src/cmd/ksh93/tests/coprocess.sh
index 0764f9e77..1cc473334 100755
--- a/src/cmd/ksh93/tests/coprocess.sh
+++ b/src/cmd/ksh93/tests/coprocess.sh
@@ -109,7 +109,7 @@ do
 	$cat |&
 	!
 	chmod +x $file
-	sleep 10 |&
+	sleep 1 |&
 	$file 2> /dev/null || err_exit "parent $cat coprocess prevents script coprocess"
 	exec 5<&p 6>&p
 	exec 5<&- 6>&-
@@ -119,15 +119,15 @@ do
 	cop=$!
 	exp=Done
 	print -p $'print hello | '$cat$'\nprint '$exp
-	read -t 5 -p
-	read -t 5 -p
+	read -t 1 -p
+	read -t 1 -p
 	got=$REPLY
 	if	[[ $got != $exp ]]
 	then	err_exit "${SHELL-ksh} $cat coprocess io failed -- got '$got', expected '$exp'"
 	fi
 	exec 5<&p 6>&p
 	exec 5<&- 6>&-
-	{ sleep 4; kill $cop; } 2>/dev/null &
+	{ sleep .4; kill $cop; } 2>/dev/null &
 	spy=$!
 	if	wait $cop 2>/dev/null
 	then	kill $spy 2>/dev/null
@@ -140,15 +140,15 @@ do
 	echo line2 | grep 'line1'
 	} |&
 	SECONDS=0 count=0
-	while	read -p -t 10 line
+	while	read -p -t 1 line
 	do	((count++))
 	done
-	if	(( SECONDS > 8 ))
+	if	(( SECONDS > .8 ))
 	then	err_exit "$cat coprocess read -p hanging (SECONDS=$SECONDS count=$count)"
 	fi
 	wait $!
 	
-	( sleep 3 |& sleep 1 && kill $!; sleep 1; sleep 3 |& sleep 1 && kill $! ) ||
+	( sleep .3 |& sleep .1 && kill $!; sleep .1; sleep .3 |& sleep .1 && kill $! ) ||
 		err_exit "$cat coprocess cleanup not working correctly"
 	{ : |& } 2>/dev/null ||
 		err_exit "subshell $cat coprocess lingers in parent"
@@ -166,7 +166,7 @@ do
 			wait $!
 		done
 		print
-	) 2>/dev/null | read -t 10 r
+	) 2>/dev/null | read -t 1 r
 	[[ $r == $e ]] || err_exit "$cat coprocess timing bug -- expected $e, got '$r'"
 	
 	r=
@@ -174,21 +174,21 @@ do
 		integer i
 		for ((i = 1; i <= N; i++))
 		do	print $i |&
-			sleep 0.01
+			sleep 0.001
 			r=$r$($cat <&p)
 			wait $!
 		done
 		print $r
-	) 2>/dev/null | read -t 10 r
+	) 2>/dev/null | read -t 1 r
 	[[ $r == $e ]] || err_exit "$cat coprocess command substitution bug -- expected $e, got '$r'"
 	
 	(
 		$cat |&
-		sleep 0.01
+		sleep 0.001
 		exec 6>&p
 		print -u6 ok
 		exec 6>&-
-		sleep 2
+		sleep .2
 		kill $! 2> /dev/null
 	) && err_exit "$cat coprocess with subshell would hang"
 	for sig in IOT ABRT
@@ -198,12 +198,12 @@ do
 					pid=\$!
 					trap "print TRAP" \$sig
 					(
-						sleep 2
+						sleep .2
 						kill -\$sig \$\$
-						sleep 2
+						sleep .2
 						kill -\$sig \$\$
 						kill \$pid
-						sleep 2
+						sleep .2
 						kill \$\$
 					) &
 					while	read -p || ((\$? > 256))
@@ -218,7 +218,7 @@ do
 	done
 	
 	trap 'sleep_pid=; kill $pid; err_exit "$cat coprocess 1 hung"' TERM
-	{ sleep 5; kill $$; } &
+	{ sleep .5; kill $$; } &
 	sleep_pid=$!
 	$cat |&
 	pid=$!
@@ -232,7 +232,7 @@ do
 	[[ $sleep_pid ]] && kill $sleep_pid
 	
 	trap 'sleep_pid=; kill $pid; err_exit "$cat coprocess 2 hung"' TERM
-	{ sleep 5; kill $$; } &
+	{ sleep .5; kill $$; } &
 	sleep_pid=$!
 	$cat |&
 	pid=$!
@@ -244,7 +244,7 @@ do
 	[[ $sleep_pid ]] && kill $sleep_pid
 	
 	trap 'sleep_pid=; kill $pid; err_exit "$cat coprocess 3 hung"' TERM
-	{ sleep 5; kill $$; } &
+	{ sleep .5; kill $$; } &
 	sleep_pid=$!
 	$cat |&
 	pid=$!
diff --git a/src/cmd/ksh93/tests/functions.sh b/src/cmd/ksh93/tests/functions.sh
index 83df8f10d..562821000 100755
--- a/src/cmd/ksh93/tests/functions.sh
+++ b/src/cmd/ksh93/tests/functions.sh
@@ -981,10 +981,17 @@ function _Dbg_debug_trap_handler
 	done
 }
 
+(
+: 'Disabling xtrace while running _Dbg_* functions'
+set +x	# TODO: the _Dbg_* functions are incompatible with xtrace. To expose the regression
+	# test failures, run 'bin/shtests -x -p functions'. Is this a bug in ksh?
 ((baseline=LINENO+2))
 trap '_Dbg_debug_trap_handler' DEBUG
 .  $tmp/debug foo bar
 trap '' DEBUG
+exit $Errors
+)
+Errors=$?
 
 caller() {
   integer .level=.sh.level .max=.sh.level-1
diff --git a/src/cmd/ksh93/tests/io.sh b/src/cmd/ksh93/tests/io.sh
index d84491247..8b2721604 100755
--- a/src/cmd/ksh93/tests/io.sh
+++ b/src/cmd/ksh93/tests/io.sh
@@ -99,6 +99,7 @@ fi
 
 # 2004-11-25 ancient /dev/fd/N redirection bug fix
 got=$(
+	set +x
 	{
 		print -n 1
 		print -n 2 > ${FDFS[fdfs].dir}/2
@@ -338,16 +339,16 @@ read -n3 a <<!
 abcdefg
 !
 [[ $a == abc ]] || err_exit 'read -n3 here-document not working'
-(print -n a; sleep 1; print -n bcde) | { read -N3 a; read -N1 b;}
+(print -n a; sleep .1; print -n bcde) | { read -N3 a; read -N1 b;}
 [[ $a == abc ]] || err_exit 'read -N3 from pipe not working'
 [[ $b == d ]] || err_exit 'read -N1 from pipe not working'
-(print -n a; sleep 1; print -n bcde) 2>/dev/null |read -n3 a
+(print -n a; sleep .1; print -n bcde) 2>/dev/null |read -n3 a
 [[ $a == a ]] || err_exit 'read -n3 from pipe not working'
 if	mkfifo $tmp/fifo 2> /dev/null
-then	(print -n a; sleep 2; print -n bcde) > $tmp/fifo &
+then	(print -n a; sleep .2; print -n bcde) > $tmp/fifo &
 	{
-	read -u5 -n3 -t3 a || err_exit 'read -n3 from fifo timed out'
-	read -u5 -n1 -t3 b || err_exit 'read -n1 from fifo timed out'
+	read -u5 -n3 -t1 a || err_exit 'read -n3 from fifo timed out'
+	read -u5 -n1 -t1 b || err_exit 'read -n1 from fifo timed out'
 	} 5< $tmp/fifo
 	exp=a
 	got=$a
@@ -358,10 +359,10 @@ then	(print -n a; sleep 2; print -n bcde) > $tmp/fifo &
 	rm -f $tmp/fifo
 	wait
 	mkfifo $tmp/fifo 2> /dev/null
-	(print -n a; sleep 2; print -n bcde) > $tmp/fifo &
+	(print -n a; sleep .2; print -n bcde) > $tmp/fifo &
 	{
-	read -u5 -N3 -t3 a || err_exit 'read -N3 from fifo timed out'
-	read -u5 -N1 -t3 b || err_exit 'read -N1 from fifo timed out'
+	read -u5 -N3 -t1 a || err_exit 'read -N3 from fifo timed out'
+	read -u5 -N1 -t1 b || err_exit 'read -N1 from fifo timed out'
 	} 5< $tmp/fifo
 	exp=abc
 	got=$a
@@ -373,16 +374,16 @@ then	(print -n a; sleep 2; print -n bcde) > $tmp/fifo &
 fi
 (
 	print -n 'prompt1: '
-	sleep .1
+	sleep .01
 	print line2
-	sleep .1
+	sleep .01
 	print -n 'prompt2: '
-	sleep .1
+	sleep .01
 ) | {
-	read -t2 -n 1000 line1
-	read -t2 -n 1000 line2
-	read -t2 -n 1000 line3
-	read -t2 -n 1000 line4
+	read -t1 -n 1000 line1
+	read -t1 -n 1000 line2
+	read -t1 -n 1000 line3
+	read -t1 -n 1000 line4
 }
 [[ $? == 0 ]]		 	&& err_exit 'should have timed out'
 [[ $line1 == 'prompt1: ' ]] 	|| err_exit "line1 should be 'prompt1: '"
@@ -410,7 +411,7 @@ do	a=$1
 	shift 4
 	for ((i = 0; i < 2; i++))
 	do	for lc_all in C $lc_utf8
-		do	g=$(LC_ALL=$lc_all $SHELL -c "{ print -n '$a'; sleep 0.2; print -n '$b'; sleep 0.2; } | { read ${o[i]} a; print -n \$a; read a; print -n \ \$a; }")
+		do	g=$(LC_ALL=$lc_all $SHELL -c "{ print -n '$a'; sleep .02; print -n '$b'; sleep .02; } | { read ${o[i]} a; print -n \$a; read a; print -n \ \$a; }")
 			[[ $g == "${e[i]}" ]] || err_exit "LC_ALL=$lc_all read ${o[i]} from pipe '$a $b' failed -- expected '${e[i]}', got '$g'"
 		done
 	done
@@ -437,12 +438,14 @@ then	export LC_ALL=$lc_utf8
 	fi
 fi
 
-exec 3<&2
 file=$tmp/file
+(
+: disabling xtrace so we can redirect stderr for this test
+set +x
 redirect 5>$file 2>&5
 print -u5 -f 'This is a test\n'
 print -u2 OK
-exec 2<&3
+)
 exp=$'This is a test\nOK'
 got=$(< $file)
 [[ $got == $exp ]] || err_exit "output garbled when stderr is duped -- expected $(printf %q "$exp"), got $(printf %q "$got")"
diff --git a/src/cmd/ksh93/tests/locale.sh b/src/cmd/ksh93/tests/locale.sh
index c95635910..b43a5f2cb 100755
--- a/src/cmd/ksh93/tests/locale.sh
+++ b/src/cmd/ksh93/tests/locale.sh
@@ -200,11 +200,11 @@ got="$(<out)"
 # multibyte identifiers
 
 exp=OK
-got=$(LC_ALL=C.UTF-8 $SHELL -c $'\u[5929]=OK; print ${\u[5929]}' 2>&1)
+got=$(set +x; LC_ALL=C.UTF-8 $SHELL -c $'\u[5929]=OK; print ${\u[5929]}' 2>&1)
 [[ $got == "$exp" ]] || err_exit "multibyte variable definition/expansion failed -- expected '$exp', got '$got'"
-got=$(LC_ALL=C.UTF-8 $SHELL -c $'function \u[5929]\n{\nprint OK;\n}; \u[5929]' 2>&1)
+got=$(set +x; LC_ALL=C.UTF-8 $SHELL -c $'function \u[5929]\n{\nprint OK;\n}; \u[5929]' 2>&1)
 [[ $got == "$exp" ]] || err_exit "multibyte ksh function definition/execution failed -- expected '$exp', got '$got'"
-got=$(LC_ALL=C.UTF-8 $SHELL -c $'\u[5929]()\n{\nprint OK;\n}; \u[5929]' 2>&1)
+got=$(set +x; LC_ALL=C.UTF-8 $SHELL -c $'\u[5929]()\n{\nprint OK;\n}; \u[5929]' 2>&1)
 [[ $got == "$exp" ]] || err_exit "multibyte posix function definition/execution failed -- expected '$exp', got '$got'"
 
 # this locale is supported by ast on all platforms
diff --git a/src/cmd/ksh93/tests/options.sh b/src/cmd/ksh93/tests/options.sh
index a8abb2d86..95a467530 100755
--- a/src/cmd/ksh93/tests/options.sh
+++ b/src/cmd/ksh93/tests/options.sh
@@ -73,7 +73,7 @@ then
 		got=$(printf %q "$got")
 		err_exit "\$ENV file &>/dev/null does not redirect stdout -- expected '', got $got"
 	fi
-	got=$($SHELL -E -c : 2>&1 >/dev/null)
+	got=$(set +x; $SHELL -E -c : 2>&1 >/dev/null)
 	if	[[ $got != *nonstandard* || $got == *$'\n'* ]]
 	then
 		got=$(printf %q "$got")
@@ -151,11 +151,11 @@ then
 else
 	[[ $(print env_hit | HOME=$tmp $SHELL 2>&1) == "OK" ]] &&
 		err_exit 'nointeractive shell reads $HOME/.kshrc file'
-	[[ $(print env_hit | HOME=$tmp $SHELL -E 2>&1) == "OK" ]] ||
+	[[ $(set +x; print env_hit | HOME=$tmp $SHELL -E 2>&1) == "OK" ]] ||
 		err_exit '-E ignores $HOME/.kshrc file'
 	[[ $(print env_hit | HOME=$tmp $SHELL +E 2>&1) == "OK" ]] &&
 		err_exit '+E reads $HOME/.kshrc file'
-	[[ $(print env_hit | HOME=$tmp $SHELL --rc 2>&1) == "OK" ]] ||
+	[[ $(set +x; print env_hit | HOME=$tmp $SHELL --rc 2>&1) == "OK" ]] ||
 		err_exit '--rc ignores $HOME/.kshrc file'
 	[[ $(print env_hit | HOME=$tmp $SHELL --norc 2>&1) == "OK" ]] &&
 		err_exit '--norc reads $HOME/.kshrc file'
@@ -368,7 +368,7 @@ pipeline=(
 	( nopipefail=1 pipefail=1 command='true|true|false' )
 	( nopipefail=1 pipefail=1 command='false|false|false' )
 	( nopipefail=0 pipefail=0 command='true|true|true' )
-	( nopipefail=0 pipefail=0 command='print hi|(sleep 1;"$bincat")>/dev/null' )
+	( nopipefail=0 pipefail=0 command='print hi|(sleep .1;"$bincat")>/dev/null' )
 )
 set --nopipefail
 for ((i = 0; i < ${#pipeline[@]}; i++ ))
@@ -443,10 +443,10 @@ export ENV= PS1="(:$$:)"
 histfile=$tmp/history
 exp=$(HISTFILE=$histfile $SHELL -c $'function foo\n{\ncat\n}\ntype foo')
 for var in HISTSIZE HISTFILE
-do	got=$( ( HISTFILE=$histfile $SHELL +E -ic $'unset '$var$'\nfunction foo\n{\ncat\n}\ntype foo\nexit' ) 2>&1 )
+do	got=$( set +x; ( HISTFILE=$histfile $SHELL +E -ic $'unset '$var$'\nfunction foo\n{\ncat\n}\ntype foo\nexit' ) 2>&1 )
 	got=${got##*"$PS1"} 
 	[[ $got == "$exp" ]] || err_exit "function definition inside (...) with $var unset fails -- got '$got', expected '$exp'"
-	got=$( { HISTFILE=$histfile $SHELL +E -ic $'unset '$var$'\nfunction foo\n{\ncat\n}\ntype foo\nexit' ;} 2>&1 )
+	got=$( set +x; { HISTFILE=$histfile $SHELL +E -ic $'unset '$var$'\nfunction foo\n{\ncat\n}\ntype foo\nexit' ;} 2>&1 )
 	got=${got##*"$PS1"} 
 	[[ $got == "$exp" ]] || err_exit "function definition inside {...;} with $var unset fails -- got '$got', expected '$exp'"
 done
diff --git a/src/cmd/ksh93/tests/path.sh b/src/cmd/ksh93/tests/path.sh
index 8c37e3a71..70d0b0cad 100755
--- a/src/cmd/ksh93/tests/path.sh
+++ b/src/cmd/ksh93/tests/path.sh
@@ -342,7 +342,7 @@ function foo
 
 # whence -q bug fix
 $SHELL -c 'whence -q cat' & pid=$!
-sleep 3
+sleep .1
 kill $! 2> /dev/null && err_exit 'whence -q appears to be hung'
 
 FPATH=$PWD
diff --git a/src/cmd/ksh93/tests/shtests b/src/cmd/ksh93/tests/shtests
index 138be48f0..fdbcccf96 100755
--- a/src/cmd/ksh93/tests/shtests
+++ b/src/cmd/ksh93/tests/shtests
@@ -207,7 +207,7 @@ done
 shift $OPTIND-1
 
 if	(( debug )) || [[ $trace ]]
-then	export PS4=':$LINENO: '
+then	export PS4='+ [${SECONDS:+${SECONDS%????}s|}${.sh.subshell:+S${.sh.subshell},}${.sh.file:+${.sh.file#${.sh.file%/*/*}/},}${.sh.fun:+${.sh.fun},}${LINENO:+L$LINENO,}e$?] '
 	if	(( debug ))
 	then	set -x
 	fi
diff --git a/src/cmd/ksh93/tests/sigchld.sh b/src/cmd/ksh93/tests/sigchld.sh
index 3b352652c..30ba7637d 100755
--- a/src/cmd/ksh93/tests/sigchld.sh
+++ b/src/cmd/ksh93/tests/sigchld.sh
@@ -26,7 +26,7 @@ function err_exit
 
 alias err_exit='err_exit $LINENO'
 
-float DELAY=${1:-0.2}
+float DELAY=${1:-0.02}
 integer FOREGROUND=10 BACKGROUND=2 Errors=0
 
 tmp=$(
@@ -82,7 +82,7 @@ then
 		integer running=0 maxrunning=0
 		trap "((running--))" CHLD
 		for ((i=0; i<JOBCOUNT; i++))
-		do	sleep 1 &
+		do	sleep .1 &
 			if	((++running > maxrunning))
 			then	((maxrunning=running))
 			fi
@@ -101,13 +101,13 @@ then
 			unset proc[\$!]
 		" CHLD
 
-		{ sleep 3; print a; exit 1; } &
+		{ sleep .3; print a; exit 1; } &
 		proc[$!]=( name=a status=1 )
 
-		{ sleep 2; print b; exit 2; } &
+		{ sleep .2; print b; exit 2; } &
 		proc[$!]=( name=b status=2 )
 
-		{ sleep 1; print c; exit 3; } &
+		{ sleep .1; print c; exit 3; } &
 		proc[$!]=( name=c status=3 )
 
 		while	(( ${#proc[@]} ))
@@ -120,8 +120,8 @@ then
 fi
 
 {
-got=$( ( sleep 1;print $'\n') | $SHELL -c 'function handler { : ;}
-	trap handler CHLD; sleep .3 & IFS= read; print good')
+got=$( ( sleep .1;print $'\n') | $SHELL -c 'function handler { : ;}
+	trap handler CHLD; sleep .03 & IFS= read; print good')
 } 2> /dev/null
 [[ $got == good ]] || err_exit 'SIGCLD handler effects read behavior'
 
@@ -129,9 +129,9 @@ set -- $(
 	(
 	$SHELL -xc $'
 		trap \'wait $!; print $! $?\' CHLD
-		{ sleep 0.1; exit 9; } &
+		{ sleep 0.01; exit 9; } &
 		print $!
-		sleep 0.5
+		sleep 0.05
 	'
 	) 2>/dev/null; print $?
 )
@@ -155,11 +155,11 @@ done
 (( d==2000 )) ||  err_exit "trap '' CHLD  causes side effects d=$d"
 trap - CHLD
 
-x=$($SHELL 2> /dev/null -ic '/dev/null/notfound; sleep .5 & sleep 1;jobs')
+x=$($SHELL 2> /dev/null -ic '/dev/null/notfound; sleep .05 & sleep .1;jobs')
 [[ $x == *Done* ]] || err_exit 'SIGCHLD blocked after notfound'
-x=$($SHELL 2> /dev/null  -ic 'kill -0 12345678901234567876; sleep .5 & sleep 1;jobs')
+x=$($SHELL 2> /dev/null  -ic 'kill -0 12345678901234567876; sleep .05 & sleep .1;jobs')
 [[ $x == *Done* ]] || err_exit 'SIGCHLD blocked after error message'
-print 'set -o monitor;sleep .5 & sleep 1;jobs' > $tmp/foobar
+print 'set -o monitor;sleep .05 & sleep .1;jobs' > $tmp/foobar
 chmod +x $tmp/foobar
 x=$($SHELL  -c "echo | $tmp/foobar")
 [[ $x == *Done* ]] || err_exit 'SIGCHLD blocked for script at end of pipeline'
diff --git a/src/cmd/ksh93/tests/signal.sh b/src/cmd/ksh93/tests/signal.sh
index ae6021c12..260ef7918 100755
--- a/src/cmd/ksh93/tests/signal.sh
+++ b/src/cmd/ksh93/tests/signal.sh
@@ -56,7 +56,8 @@ do	if	! n=$(kill -l $s 2>/dev/null)
 done
 
 (
-	set --pipefail
+	: disabling xtrace for this test
+	set +x --pipefail
 	{
 		$SHELL 2> out2 <<- \EOF
 			g=false
@@ -67,6 +68,7 @@ done
 		EOF
 	} | head > /dev/null
 	(( $? == 0)) ||   err_exit "SIGPIPE with wrong error code $?"
+	# The below is kind of bogus as the err_exit from a bg job is never counterd. But see extra check below.
 	[[ $(<out2) == $'PIPED\nPIPED' ]] || err_exit 'SIGPIPE output on standard error is not correct'
 ) &
 cop=$!
@@ -74,7 +76,7 @@ cop=$!
 spy=$!
 if	wait $cop 2>/dev/null
 then	kill $spy 2>/dev/null
-else	err_exit "pipe with --pipefail PIPE trap hangs"
+else	err_exit "pipe with --pipefail PIPE trap hangs or produced an error"
 fi
 wait
 rm -f out2
diff --git a/src/cmd/ksh93/tests/subshell.sh b/src/cmd/ksh93/tests/subshell.sh
index a393b8db5..37da42fc4 100755
--- a/src/cmd/ksh93/tests/subshell.sh
+++ b/src/cmd/ksh93/tests/subshell.sh
@@ -19,14 +19,15 @@
 ########################################################################
 function err_exit
 {
-	print -u$Error_fd -n "\t"
-	print -u$Error_fd -r ${Command}[$1]: "${@:2}"
+	print -u2 -n "\t"
+	print -u2 -r ${Command}[$1]: "${@:2}"
 	(( Errors+=1 ))
 }
 alias err_exit='err_exit $LINENO'
 
 Command=${0##*/}
-integer Errors=0 Error_fd=2
+integer Errors=0
+typeset -F SECONDS  # for fractional seconds in PS4
 
 tmp=$(
 	d=${TMPDIR:-/tmp}/ksh93.subshell.$$.${RANDOM:-0}
@@ -40,6 +41,13 @@ trap 'cd / && rm -rf "$tmp"' EXIT
 builtin getconf
 bincat=$(PATH=$(getconf PATH) whence -p cat)
 binecho=$(PATH=$(getconf PATH) whence -p echo)
+# make an external 'sleep' command that supports fractional seconds
+binsleep=$tmp/.sleep.sh  # hide to exclude from simple wildcard expansion
+cat >"$binsleep" <<EOF
+#!$SHELL
+sleep "\$@"
+EOF
+chmod +x "$binsleep"
 
 z=()
 z.foo=( [one]=hello [two]=(x=3 y=4) [three]=hi)
@@ -102,9 +110,6 @@ unset l
 )
 [[ ${l+foo} != foo ]] || err_exit 'l should be unset'
 
-Error_fd=9
-eval "exec $Error_fd>&2 2>/dev/null"
-
 TEST_notfound=notfound
 while	whence $TEST_notfound >/dev/null 2>&1
 do	TEST_notfound=notfound-$RANDOM
@@ -220,7 +225,7 @@ do	for TEST_exec in '' 'exec'
 			sleep 2
 			kill -KILL $$
 		} &
-		'"$TEST_test"'
+		{ '"$TEST_test"'; } 2>/dev/null
 		kill $!
 		print ok
 		')
@@ -394,7 +399,7 @@ do	cat $tmp/buf $tmp/buf > $tmp/tmp
 		wait $m
 		h=$?
 		kill -9 $k
-		wait $k
+		{ wait $k; } 2>/dev/null  # suppress 'wait: $pid: Killed'
 		got=$(<$tmp/out)
 		if	[[ ! $got ]] && (( h ))
 		then	got=HUNG
@@ -427,7 +432,7 @@ done
 # specifics -- there's more?
 
 {
-	cmd='{ exec 5>/dev/null; print "$(eval ls -d . 2>&1 1>&5)"; } >$tmp/out &'
+	cmd='{ exec 5>/dev/null; print "$(set +x; eval ls -d . 2>&1 1>&5)"; } >$tmp/out &'
 	eval $cmd
 	m=$!
 	{ sleep 4; kill -9 $m; } &
@@ -447,13 +452,11 @@ then	err_exit "eval '$cmd' failed -- expected '$exp', got '$got'"
 fi
 
 float t1=$SECONDS
-sleep=$(whence -p sleep)
-if	[[ $sleep ]]
-then
-	$SHELL -c "( $sleep 5 </dev/null >/dev/null 2>&1 & );exit 0" | cat 
-	(( (SECONDS-t1) > 4 )) && err_exit '/bin/sleep& in subshell hanging'
-	((t1=SECONDS))
-fi
+
+$SHELL -c '( "$1" 5 </dev/null >/dev/null 2>&1 & );exit 0' x "$binsleep" | cat 
+(( (SECONDS-t1) > 4 )) && err_exit '/bin/sleep& in subshell hanging'
+((t1=SECONDS))
+
 $SHELL -c '( sleep 5 </dev/null >/dev/null 2>&1 & );exit 0' | cat 
 (( (SECONDS-t1) > 4 )) && err_exit 'sleep& in subshell hanging'
 
@@ -483,7 +486,7 @@ $SHELL -c 'sleep 20 & pid=$!; { x=$( ( seq 60000 ) );kill -9 $pid;}&;wait $pid'
 
 (.sh.foo=foobar)
 [[ ${.sh.foo} == foobar ]] && err_exit '.sh subvariables in subshells remain set'
-[[ $($SHELL -c 'print 1 | : "$("$bincat" <("$bincat"))"') ]] && err_exit 'process substitution not working correctly in subshells'
+[[ $(export bincat; $SHELL -c 'print 1 | : "$("$bincat" <("$bincat"))"') ]] && err_exit 'process substitution not working correctly in subshells'
 
 # config hang bug
 integer i
@@ -542,7 +545,7 @@ $SHELL <<- \EOF
 	(( ${#out} == 96011 )) || err_exit "\${#out} is ${#out} should be 96011"
 EOF
 } & pid=$!
-$SHELL -c "{ sleep 4 && kill $pid ;}" 2> /dev/null
+$SHELL -c "{ sleep .4 && kill $pid ;}" 2> /dev/null
 (( $? == 0 )) &&  err_exit 'process has hung'
 
 {
@@ -613,7 +616,7 @@ $SHELL <<- \EOF
 	wc=$(whence wc) head=$(whence head)
 	print > /dev/null  $( ( $head -c 1 /dev/zero | ( $wc -c) 3>&1 ) 3>&1) &
 	pid=$!
-	sleep 2
+	sleep .2
 	kill -9 $! 2> /dev/null && err_exit '/dev/zero in command substitution hangs'
 	wait $!
 EOF
@@ -685,13 +688,13 @@ expect=$'sub3\nok_nonexistent\nsub2\nsub1\nmainfunction'
 
 alias al="echo 'mainalias'"
 
-(unalias al; alias al >/dev/null) && err_exit 'alias fails to be unset in subshell'
+(unalias al; alias al 2>/dev/null) && err_exit 'alias fails to be unset in subshell'
 
-v=$(unalias al; alias al >/dev/null) && err_exit 'alias fails to be unset in comsub'
+v=$(unalias al; alias al 2>/dev/null) && err_exit 'alias fails to be unset in comsub'
 
 [[ $(eval 'al') == 'mainalias' ]] || err_exit 'main alias fails to survive unset in subshell(s)'
 
-v=${ eval 'al'; unalias al 2>&1; } && [[ $v == 'mainalias' ]] && ! alias al >/dev/null \
+v=${ eval 'al'; unalias al 2>&1; } && [[ $v == 'mainalias' ]] && ! alias al 2>/dev/null \
 || err_exit 'main shell alias wrongly survives unset within ${ ...; }'
 
 # ...alias can be redefined in subshell
diff --git a/src/cmd/ksh93/tests/substring.sh b/src/cmd/ksh93/tests/substring.sh
index d33b7f9a8..b74c18143 100755
--- a/src/cmd/ksh93/tests/substring.sh
+++ b/src/cmd/ksh93/tests/substring.sh
@@ -26,7 +26,10 @@ function err_exit
 alias err_exit='err_exit $LINENO'
 
 Command=${0##*/}
-integer Errors=0 j=4
+integer Errors=0
+tmpPS4='+ [temp_PS4|L$LINENO|e$?] '  # used to avoid interference to ${.sh.match} from $PS4 set by shtests
+
+integer j=4
 base=/home/dgk/foo//bar
 string1=$base/abcabcabc
 if	[[ ${string1:0} != "$string1" ]]
@@ -261,6 +264,9 @@ foo='foo+bar+'
 [[ $(print -r -- ${foo//+/"|"}) != 'foo|bar|' ]] && err_exit '${foobar//+/"|"}'
 [[ $(print -r -- "${foo//+/'|'}") != 'foo|bar|' ]] && err_exit '"${foobar//+/'"'|'"'}"'
 [[ $(print -r -- "${foo//+/"|"}") != 'foo|bar|' ]] && err_exit '"${foobar//+/"|"}"'
+
+(
+PS4=$tmpPS4
 unset x
 x=abcedfg
 : ${x%@(d)f@(g)}
@@ -270,6 +276,10 @@ x=abcedfg
 x=abcedddfg
 : ${x%%+(d)f@(g)}
 [[ ${.sh.match[1]} == ddd ]] || err_exit '.sh.match[1] not ddd'
+exit $Errors
+)
+Errors=$?
+
 unset a b
 a='\[abc @(*) def\]'
 b='[abc 123 def]'
@@ -296,10 +306,16 @@ integer i
 for((i=0; i < ${#string}; i++))
 do	pattern+='@(?)'
 done
+
+(
+PS4=$tmpPS4
 [[ $(string=$string $SHELL -c  ": \${string/$pattern/}; print \${.sh.match[26]}") == Z ]] || err_exit -u2 'sh.match[26] not Z'
 : ${string/$pattern/}
 (( ${#.sh.match[@]} == 53 )) || err_exit '.sh.match has wrong number of elements'
 [[ ${.sh.match[@]:2:4} == 'B C D E'  ]] || err_exit '${.sh.match[@]:2:4} incorrect'
+exit $Errors
+)
+Errors=$?
 
 D=$';' E=$'\\\\' Q=$'"' S=$'\'' M='nested pattern substitution failed'
 
@@ -497,7 +513,7 @@ pattern=00
 var=100
 [[ $( print $(( ${var%%00} )) ) == 1 ]] || err_exit "arithmetic with embedded patterns fails"
 [[ $( print $(( ${var%%$pattern} )) ) == 1 ]] || err_exit "arithmetic with embedded pattern variables fails"
-if	[[ ax == @(a)* ]] && [[ ${.sh.match[1]:0:${#.sh.match[1]}}  != a ]]
+if	(PS4=$tmpPS4; [[ ax == @(a)* ]] && [[ ${.sh.match[1]:0:${#.sh.match[1]}}  != a ]])
 then	err_exit '${.sh.match[1]:1:${#.sh.match[1]}} not expanding correctly'
 fi
 
@@ -586,6 +602,9 @@ got=$($SHELL -c 'A=""; B="B"; for I in ${A[@]} ${B[@]}; do echo "\"$I\""; done')
 A='|'
 [[ $A == $A ]] || err_exit 'With A="|",  [[ $A == $A ]] does not match'
 
+(
+PS4=$tmpPS4
+
 x="111 222 333 444 555 666"
 [[ $x == ~(E)(...).(...).(...) ]]
 [[ -v .sh.match[0] ]] ||   err_exit '[[ -v .sh.match[0] ]] should be true'
@@ -597,6 +616,10 @@ x="foo bar"
 dummy=${x/~(E)(*)/}
 [[ ${ print -v .sh.match;} ]] && err_exit 'print -v should show .sh.match empty when there are no matches'
 
+exit $Errors
+)
+Errors=$?
+
 if	$SHELL -c 'set 1 2 3 4 5 6 7 8 9 10 11 12; : ${##[0-9]}' 2>/dev/null
 then	set 1 2 3 4 5 6 7 8 9 10 11 12
 	[[ ${##[0-9]} == 2 ]] || err_exit '${##[0-9]} should be 2 with $#==12'
@@ -614,16 +637,21 @@ fi
 
 function foo
 {
-	typeset x="123 456 789 abc"
+	typeset PS4=$tmpPS4 x="123 456 789 abc"
 	typeset dummy="${x/~(E-g)([[:digit:]][[:digit:]])((X)|([[:digit:]]))([[:blank:]])/_}"
 	exp=$'(\n\t[0]=\'123 \'\n\t[1]=12\n\t[2]=3\n\t[4]=3\n\t[5]=\' \'\n)'
 	[[ $(print -v .sh.match) == "$exp" ]] || err_exit '.sh.match not correct with alternations'
 }
 foo
 
+(
+PS4=$tmpPS4
 x="a 1 b"
 d=${x/~(E)(([[:digit:]])[[:space:]]*|([[:alpha:]]))/X}
 [[ $(print -v .sh.match) == $'(\n\t[0]=a\n\t[1]=a\n\t[3]=a\n)' ]] || err_exit '.sh.match not sparse'
+exit $Errors
+)
+Errors=$?
 
 unset v
 typeset -a arr=( 0 1 2 3 4 )
@@ -654,11 +682,16 @@ do	err_exit "\${@:0:-1} should not generate ${v:-empty_string}"
 	break
 done
 
+(
+PS4=$tmpPS4
 unset v d
 v=abbbc
 d="${v/~(E)b{2,4}/dummy}"
 [[ ${.sh.match} == bbb ]] || err_exit '.sh.match wrong after ${s/~(E)b{2,4}/dummy}'
 [[ $d == adummyc ]] || err_exit '${s/~(E)b{2,4}/dummy} not working'
+exit $Errors
+)
+Errors=$?
 
-
+# ======
 exit $((Errors<125?Errors:125))
diff --git a/src/cmd/ksh93/tests/variables.sh b/src/cmd/ksh93/tests/variables.sh
index cd7aaa364..ecf0347d2 100755
--- a/src/cmd/ksh93/tests/variables.sh
+++ b/src/cmd/ksh93/tests/variables.sh
@@ -47,9 +47,10 @@ if	(( RANDOM==RANDOM || $RANDOM==$RANDOM ))
 then	err_exit RANDOM variable not working
 fi
 # SECONDS
-sleep 3
-if	(( SECONDS < 2 ))
-then	err_exit SECONDS variable not working
+let SECONDS=0.0
+sleep .001
+if	(( SECONDS < .001 ))
+then	err_exit "either 'sleep' or \$SECONDS not working"
 fi
 # _
 set abc def
@@ -217,6 +218,7 @@ x error"
 	then	err_exit "\${#$i} not correct"
 	fi
 done
+kill -s 0 $! || err_exit '$! does not point to latest asynchronous process'
 kill $!
 unset x
 CDPATH=/
@@ -433,12 +435,12 @@ fi
 function foo
 {
 	typeset SECONDS=0
-	sleep 1.5
+	sleep .002
 	print $SECONDS
 
 }
 x=$(foo)
-(( x >1 && x < 2 ))
+(( x >.001 && x < .01 ))
 '
 } 2> /dev/null   || err_exit 'SECONDS not working in function'
 cat > $tmp/script <<-\!