Code:
[~]# cat /ports/devel/ccache/pkg-descr
ccache is a compiler cache. It acts as a caching pre-processor to C/C++
compilers, using the -E compiler switch and a hash to detect when a
compilation can be satisfied from cache. This often results in a 5 to 10
times speedup in common compilations.
WWW: http://ccache.samba.org/
So, it's just a cache, it doesn't speed up compilation the first time (It may in fact slow it a bit).