I have had the same issue since I got my phone in April. If my internal memory falls below 200 mg (even at 197), the phone lag is significant. It will take up to five seconds for an app to open. I have rooted my phone and tried LFY and initially my phone was faster and I loved it. After about a month, I'm had the same problem. I wiped/factory reset three times and flashed Chevy SS v4.8; low-v 1.0Ghz kernal (I run it between 250 and 800; interactive). I'm back to the same problems. I run VERY few apps besides stock and root users apps like TiBU, Cache Mate, and ROM Manager. I have ONE word game, a task list, and a widget for the calendar. I have tried different games, task lists, and widgets so I'm fairly certain its not a particular app causing the problem. Any suggestions?