OK…you're asking this question in the Early Intel Mac forum. Most people who use Early Intel Macs, simply upgrade to Snow Leopard or Lion if they don't like the performance of Leopard.
If you DON"T have an Early Intel Mac, and are trying to use Leopard on a PowerPC Mac, then you've posted in the wrong place. However, Sorbet Leopard for PowerPC might be something to look at and there is a Leopard optimization thread you can look for (that Sorbet Leopard borrowed from). Both are in the PowerPC forum.
Let's assume though that you do have an Early Intel Mac and are wanting to stay on Leopard. Other than some basic optimization tweaks (in the thread in the PowerPC forum), you're stuck. No one took the time to make Leopard 'usable' on Intel Macs because…Snow Leopard.