X-Server 1.5.0 very sluggish
最近升到 xorg 1.5.0，某些操作 (terminal 快速更新) 會使 xserver 佔用非常多 cpu，看來是這個問題
Working on it ... right now it looks like:
XShm pixmaps got accidentally reenabled in the course of
Someone (maybe GTK, having tracked it down yet) is taking advantage
of that by creating a shared pixmap and using it as the source for
a composite operation.
That is not handled well in EXA and triggers migration of the
destination back to system memory. (*)
(*) One of the many cases where we'd be better off creating temporaries
in video memory to avoid migration.