[Bug other/60828] Compile time speedups when using tcmalloc

[trippels at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60828

--- Comment #3 from Markus Trippelsdorf <trippels at gcc dot gnu.org> ---
I've looked at more profiles during the weekend and bitmaps always
showed up on top.
As Honza said on IRC, bitmaps go into obstacks and obstacks weren't
optimized since the 80s. So it looks like tcmalloc just handles
obstacks better than the stock glibc malloc.