diff --git a/.github/workflows/scripts/setup-dependencies.sh b/.github/workflows/scripts/setup-dependencies.sh
index 440d5e8e5ac9..b40f9290f914 100755
--- a/.github/workflows/scripts/setup-dependencies.sh
+++ b/.github/workflows/scripts/setup-dependencies.sh
@@ -1,93 +1,88 @@
 #!/usr/bin/env bash
 
 set -eu
 
 function prerun() {
   echo "::group::Install build dependencies"
   # remove snap things, update+upgrade will be faster then
   for x in lxd core20 snapd; do sudo snap remove $x; done
   sudo apt-get purge snapd google-chrome-stable firefox
   # https://github.com/orgs/community/discussions/47863
   sudo apt-get remove grub-efi-amd64-bin grub-efi-amd64-signed shim-signed --allow-remove-essential
   sudo apt-get update
   sudo apt upgrade
   sudo xargs --arg-file=.github/workflows/build-dependencies.txt apt-get install -qq
   sudo apt-get clean
   sudo dmesg -c > /var/tmp/dmesg-prerun
   echo "::endgroup::"
 }
 
 function mod_build() {
   echo "::group::Generate debian packages"
   ./autogen.sh
   ./configure --enable-debug --enable-debuginfo --enable-asan --enable-ubsan
   make --no-print-directory --silent native-deb-utils native-deb-kmod
   mv ../*.deb .
   rm ./openzfs-zfs-dracut*.deb ./openzfs-zfs-dkms*.deb
   echo "$ImageOS-$ImageVersion" > tests/ImageOS.txt
   echo "::endgroup::"
 }
 
 function mod_install() {
   # install the pre-built module only on the same runner image
   MOD=`cat tests/ImageOS.txt`
   if [ "$MOD" != "$ImageOS-$ImageVersion" ]; then
     rm -f *.deb
     mod_build
   fi
 
   echo "::group::Install and load modules"
   # don't use kernel-shipped zfs modules
   sudo sed -i.bak 's/updates/extra updates/' /etc/depmod.d/ubuntu.conf
   sudo apt-get install --fix-missing ./*.deb
 
   # Native Debian packages enable and start the services
   # Stop zfs-zed daemon, as it may interfere with some ZTS test cases
   sudo systemctl stop zfs-zed
   sudo depmod -a
   sudo modprobe zfs
   sudo dmesg
   sudo dmesg -c > /var/tmp/dmesg-module-load
   echo "::endgroup::"
 
   echo "::group::Report CPU information"
   lscpu
   cat /proc/spl/kstat/zfs/chksum_bench
   echo "::endgroup::"
 
-  echo "::group::Reclaim and report disk space"
-  # remove 4GiB of images
-  sudo systemd-run docker system prune --force --all --volumes
+  echo "::group::Optimize storage for ZFS testings"
+  # remove swap and umount fast storage
+  # 89GiB -> rootfs + bootfs with ~80MB/s -> don't care
+  # 64GiB -> /mnt with 420MB/s -> new testing ssd
+  sudo swapoff -a
 
-  # remove unused software
-  sudo systemd-run --wait rm -rf \
-    "$AGENT_TOOLSDIRECTORY" \
-    /opt/* \
-    /usr/local/* \
-    /usr/share/az* \
-    /usr/share/dotnet \
-    /usr/share/gradle* \
-    /usr/share/miniconda \
-    /usr/share/swift \
-    /var/lib/gems \
-    /var/lib/mysql \
-    /var/lib/snapd
-
-  # trim the cleaned space
-  sudo fstrim /
+  # this one is fast and mounted @ /mnt
+  # -> we reformat with ext4 + move it to /var/tmp
+  DEV="/dev/disk/azure/resource-part1"
+  sudo umount /mnt
+  sudo mkfs.ext4 -O ^has_journal -F $DEV
+  sudo mount -o noatime,barrier=0 $DEV /var/tmp
+  sudo chmod 1777 /var/tmp
 
   # disk usage afterwards
-  df -h /
+  sudo df -h /
+  sudo df -h /var/tmp
+  sudo fstrim -a
   echo "::endgroup::"
 }
 
 case "$1" in
   build)
     prerun
     mod_build
     ;;
   tests)
     prerun
     mod_install
     ;;
 esac