threads.  The only difference is that, if the thread allocates enough
memory of a certain kind, it will build a thread-local free list for
objects of that kind, and allocate from that.  This greatly reduces
locking.  The thread-local free lists are refilled using 
<TT>GC_malloc_many</tt>.
<P>
An important side effect of this flag is to replace the default
spin-then-sleep lock to be replace by a spin-then-queue based implementation.
This <I>reduces performance</i> for the standard allocation functions,
thoug