Hi,
on greatwall reloaded I usually get pretty bad fps at some spots. It took the liberty of placing hint brushes and forcing a finer-grained vis process (decreased _blocksize). From what I can tell the resulting map is way faster than the original, but strangely my radiant doesn't load up the sky and the grass, so my compiles e.g. has missing sky lights (this does not impact on performance).
C.Brutail, could you compile http://savage747.sa.funpic.de/greatwall-source.zip and see if that works for you?