If you're rooted on stock ROM, you have to install Busybox manually. Go to the Market and download and run Busybox Installer, then reboot. After that do these steps:
1) Download Blade Buddy
2) Advanced Settings
3) Check the first box for hardware acceleration
4) Scroll down, Dalvik VM Heap = 64M
5) Hit Save -> Yes, then manually reboot. If you hit Apply, it's temporary until reboot.
Goodbye lag. You'll notice Sense is a lot quicker, especially scrolling through the app drawer.