Yea, also with the Evo on 2.2 you can configure it so a thread only holds so many messages before the device deletes them. I have mine set to delete messages when they hit 100.
Others may crack down on my case on this alternative but a task killer may help speed things up on your Evo as well. It will help kill processes in the background that you do not need. YES I KNOW THE EVO SHOULD BE ABLE TO HANDLE MULTITASKING ON ITS ON BY PUTTING APPS IN "SLEEP" MODE WHEN NOT IN USE. But I just feel more comfortable doing this manually, and I have noticed a bump in perfomance when I do kill multiple apps.