Try the easy stuff first. Boot to recovery, wipe cache, then reboot. Any better? If not, you need to get a handle on possible external causes by running Better Battery Stats and/or Wakelock Detector for a day or two to see what else might be going on in the background to cause the slowdown.
Also, I just noticed that you wrote, "when i open and close the app the delay is 3-5 seconds." All apps, or a particular app? If it's a particular app, did it recently update or change? Either way, if it's a single app, try uninstalling/reinstalling it.