[CaptainChaos]

I had the lagging as well. When I say lag I mean it took forever to load my SMS when I touched the icon, but texting itself did not suffer. It turned out to be something in Winterboard.

All of the "extra" stuff you see in the Cydia Packages section are dependencies that the programs have to have to run. They do not take up very much space on your hard drive however. It is not like in windows where applications are 100s of megs. Most of your tweaks and themes from Cydia are small.