You might check to see how many apps you have in the multi-tasking bar (double click the home button). If there are tons of apps "open", press and hold until they jiggle and hit the "-" to close them down. You should do this periodically.
Also, if you have several apps that are either RSS feeds or use push notifications and data updates, these are hard on your device's speed, not to mention battery life.
The most recent update seems to have made things happen more "snappy" IMO, but that might be wishful thinking. No problems with it, though.