Not perfect, but try multiple instances of
gzip < /dev/zero > /tmp/FILE
This won't hit IO so much though. dd is better for that, a variation of:
dd if=/dev/zero bs=8192 count=100000 of=/tmp/FILE
Execute the following commands 4 times
save the bellow commands under a file name then give execute permission to that file and
execute it 4 times in background
the script creates 100000 factorials...
dc << EOF
Thanks ! I'll maybe (carefully) try both at once !