No need to overclock to 1150mhz, limiting factor is still I/O. OC to 1150 is just crazy. I am happily using 600mhz and my device isn't slow. I only OC to record 720p-video and play them. even then I don't OC to insane values like 1.15 ghz. I never pass the 850 as max
I suggest to buy an microSD of class 6 (or higher)) and make an swappartition on SD and use ereswap + swappolube. Also cleanup your conversations, a big database tends to slowdown the whole device.

edit: Marmistz was a little faster, alarmed can help a lot to defrag swap. I personally use ereswap instead of swapset but I guess the endresult is the same.