So I don't know if this will fix your problem, but it sounds similar to a problem my in-laws were having when they purchased a new Ipad. Basically, I had to reconfigure the wireless router to provide the proper signal to the device. For example, it was send out G when the Ipad wanted N. Simple reconfig and reboot and all was right. I'm not sure this is the problem you are having but it seems like it would be since the new cpu is not working as well as the old cpu. Just a thought. Hope it helps.