Use -O not -O3: reduces ccan/tdb test time from 24 to 18 seconds.
[ccan] / ccan / isaac /
drwxr-xr-x   ..
-rw-r--r-- 5088 _info
-rw-r--r-- 6819 isaac.c
-rw-r--r-- 5637 isaac.h
-rw-r--r-- 6746 isaac64.c
-rw-r--r-- 5447 isaac64.h
drwxr-xr-x - test