I wrote:
Next we need a patch to filter old allocations out from new one, leaving recent allocations.
Like this enhancement to valgrind 3.5.0 for dumping "delta leaks": http://bugs.kde.org/show_bug.cgi?id=206802 Then instead of VALGRIND_DO_LEAK_CHECK in my patch, use VALGRIND_DO_ADDED_LEAK_CHECK or VALGRIND_DO_CHANGED_LEAK_CHECK.
And quoting the author, Philippe Waroquiers: "If you use the patch, it would be nice to give some feedback (how it is working, enhancements/changes you think would be good, ...)."