When is the last time you rebooted the phone?
FYI, some things (live wallpapers being one of them) do not run well on the Ascend in stock form. It has 256MB RAM and no GPU, so anything that needs a lot of memory to run and/or is graphics intensive is going to impact performance a lot.
Rooting, in and of itself, will not make the phone perform any faster, it only enables root access to the system so that you can use apps that need system-level access, such as Root Explorer, Titanium Backup, etc.
Also, I would recommend finding a memory manager app (most likely will require root) which will let you change when the OS decides to terminate applications, but don't get a task killer, as that fights against the way Android is designed to run, and *can* result in issues such as force closes, apps not working correctly, etc.
Finally, turn off anything you don't need via the Settings menu, such as Bluetooth and WiFi (when not in use), as the more apps you have running, the slower your phone will run overall. Ideally, for much improved performance, you may want to at least read up on the custom ROMs available for the Ascend. Having used Icarus, CM6 and CM7 myself, I can say that they ALL provide a major improvement over stock.