Currently investigating this situation using xdebug, profiling memory.
I also believe that it is an infrastructure problem, but out IT won’t agree with me.
Also, mysql is not an issue, such configuration holds 40,000,000 visitors daily on 3 servers.
Perhaps the PHP 5.3.1 leaks somewhere as 5.3.1 has a lot of leaks, as option, wordpress using few of these functions, that leaked memory…
or… 5.3.1 had a bug when under some circumstances not freeing memory at execution end.
Let’s prove it wrong so ??