>>Why does the internal malloc of XFree make the list grow to 157 entries in
>>one day when the other allocation method behaves a lot better?  
>
>the xfree internal malloc uses mmap/mumap i believe.   this allows
>the X server to free memory back to the system when it is no longer 
>in use.
>[...]
>>And why do things become so slow when the list length grows to 150+ entries?
>
>i don't have a clear understanding of the slowdown, so it is hard to say.
>you could try a uvm kernel and see if that makes any difference.

IIRC, the "slowdown" comes from the mmap()/munmap() taking longer and
longer ... which fits in with Chuck's hypothesis.  It looks like in
this case, the slowdown comes from the mmap/munmap calls taking longer
and longer to traverse these data structures.

--Ken