Use -O not -O3: reduces ccan/tdb test time from 24 to 18 seconds.
[ccan] / ccan / list /
drwxr-xr-x   ..
-rw-r--r-- 1422 _info
-rw-r--r-- 681 list.c
-rw-r--r-- 6922 list.h
drwxr-xr-x - test