I have jailbreaked my iPhone 4 iOS 4.1 with both limera1n and greenpois0n and the outcome is the same. My phone is really slow opening apps. (including Phone.app an SMS.app) they take about 10-15seconds to load. BUT if I start Cydia for only one second everything goes back to normal. (Please note that I have to have 3G or WI-FI access to do this) Until I let my phone sit for about 15 minutes then it's the same again. Please note that if I don't exit the apps they seem to continue working but with a bit of lag. Cydia also seems to be the only app not affected by the delay. "Loding Data" appears as quick as normal. These issues did not start to appear until about 2 weeks after I jailbreaked my phone. I have tried running "speed test" while it's in its slow state. I start the app and the app loads for like 15 seconds and then the result shows everyhting is good. All green. Since Cydia seems for fix it temporarily i figured it's jailbreak-related and not hardware-related.