Thx it's very efficent.
But ... (why is there always a 'but'?)

I made a soft using libhttrack and some calbacks. (in this 
soft : hts_init main and wrapp)
when I made a load test, with 100 threads running my  soft, 
I get out of memory very quickly and that slow the 
process...

The mem is released only when the main prog running the 
threads stop, when all threads are finished...

So I think this mem release is quite important (if you did 
it there was certainly a good reason :-) ) and not freeing 
it doesn't seem to be a good way of improving 
performance ...

thank you anyway
if you have any other idea ... :-)