> Valgrind is easier, but for real-time applications I've found that it takes a huge performance hit for some reason, at least the last time I used it.

It does, because it runs the app in an emulator.

What I did in the past (around 2005) was to write replacement malloc/calloc/realloc/free calls, put them into a libmymalloc.so, and then set LD_PRELOAD to point to libmymalloc.so.

This way I could switch between my malloc routines and the system malloc routines without recompiling the program.