The Google Perftools, especially tcmalloc (Thread Caching Malloc), can be very useful to speed up your applications, depending on your environment :
TCMalloc is faster than the glibc 2.3 malloc (available as a separate library called ptmalloc2) and other mallocs that I have tested. ptmalloc2 takes approximately 300 nanoseconds to execute a malloc/free pair on a 2.8 GHz P4 (for small objects). The TCMalloc implementation takes approximately 50 nanoseconds for the same operation pair.
Its deployment in your LAMP stack can speed up your MySQL servers, since it enhances memory allocation on threaded applications with the downside of larger memory footprints.
Here is how to use it easily... http://bit.ly/147wuw