make a pause between tests to allow hardware to empty caches

fwbench.sh

@@ -34,6 +34,7 @@ while [ $res -ne 0 ]; do
     speed=$((speed - 50))
     fwbench -b 1024 -m 0 -r $speed -s $size -o $out
     res=$?
+    usleep 500000
 done
 
 echo "Maximal speed: $speed"