Note on Magento Cache

It may be required to disable the built-in Magento cache (that is
enabled after installation by default) during active development, but please make sure that
caching is enabled on production sites as disabled cache makes the store frontend 5-6 times
slower and less responsive under load.

On the use of php accelerator:

The APC cache backend improves the results, which are 2-3 times better than the
default filesystem cache backend. The memcached cache backend shows 10-15% better results
than APC. And from the tests of Magento team, the eAccelerator cache backend shows the best results which are
5-10% faster than memcached.

Enjoy Programming!!!