diff --git a/checkapk.in b/checkapk.in
index 2b0f0c3..a9fb0ed 100644
--- a/checkapk.in
+++ b/checkapk.in
@@ -50,6 +50,9 @@ tmpdir=$(mktemp -d -t checkpkg-script.XXXXXX)
 trap "rm -rf '$tmpdir'" INT EXIT
 cd "$tmpdir" || die "failed to create temp dir"
 
+# default to pigz for unpacking
+gunzip="$(command -v pigz || echo gzip) -d"
+
 for i in $pkgname $subpackages; do
 	_pkgname=${i%%:*}
 	pkg=${_pkgname}-$pkgver-r$pkgrel
@@ -75,8 +78,10 @@ for i in $pkgname $subpackages; do
 	# For our local repo (newsize) apk info might return multiple packages, e.g. if different
 	# version of the package where build previously. Filter out this specific pkgver using awk.
 	newsize=$(apk info --repositories-file /dev/null --repository "$REPODEST"/$repo --size $_pkgname | \
-		awk "/^${pkg//+/\\+}/ { found = 1 } /^[0-9]+/ { if (found) { print \$0; exit } }")
-	oldsize=$(apk info --repositories-file $tmpdir/repositories --size $_pkgname | awk '/^[0-9]+/ { print $0 }' | head -1)
+		awk "/^${pkg//+/\\+}/ { found = 1 } /^[0-9]+/ { if (found) { print \$0; exit } }") &
+	oldsize=$(apk info --repositories-file $tmpdir/repositories --size $_pkgname | \
+		awk '/^[0-9]+/ { print $0 }' | head -1) &
+	wait
 
 	if [ "$oldsize" = "$newsize" ]; then
 		msg "No size differences for $_pkgname."
@@ -85,18 +90,18 @@ for i in $pkgname $subpackages; do
 	fi
 
 	apk fetch --quiet --repositories-file $tmpdir/repositories --stdout $_pkgname \
-		| tar -zt | grep -v '^\.SIGN\.' | sort > filelist-$_pkgname-old \
+		| $gunzip -c | tar -t | grep -v '^\.SIGN\.' | sort > filelist-$_pkgname-old \
 		|| die "failed to download old pkg, maybe run 'apk update'?"
 
-	tar -ztf "$filepath" | grep -v '^\.SIGN\.' | sort > "filelist-$_pkgname"
+	$gunzip -c "$filepath" | tar -t | grep -v '^\.SIGN\.' | sort > "filelist-$_pkgname"
 
 	diff -u "filelist-$_pkgname-old" "filelist-$_pkgname"
 
 	if diff "filelist-$_pkgname-old" "filelist-$_pkgname" | grep '\.so' > /dev/null 2>&1; then
 		mkdir -p pkg
 		cd pkg
-		tar -zxf "$filepath" > /dev/null
-		diff "../filelist-$_pkgname-old" "../filelist-$_pkgname" | awk '/>.*\.so/{$1 = ""; print $0}' | while read i; do
+		$gunzip -c "$filepath" | tar -x > /dev/null
+		diff "../filelist-$_pkgname-old" "../filelist-$_pkgname" | awk '/>.*\.so/{$1 = ""; print $0}' | while read -r i; do
 			echo "${i}: " "$(objdump -p "$i" | grep SONAME)"
 		done
 		cd ..