Originally Posted by JSanders
Remove the SD card for a few hours and see if the performance improves. Post back and let us know.
Don't turn the device off to remove the battery, leave it powered on, remove the battery and the media card, replace the battery and see how it goes.
Unfortunately this didn't help. The phone still slowed down greatly the following day. I presume the 4GB card which is on its' way won't help then, so any other suggestions appreciated.