[wjrandon]

Sounds like the word index for auto complete became corrupt, you'd be surprised how common that is with Windows Mobile devices. It'll severely slowdown your ability to type. The only known solution is to access the Word Completion settings via Settings/Personal/Input/Word Completion and click the button "Clear Stored Entries" that'll reset the word index and you should immediately notice typing works remarkably smoother. Of course you could just keep word completion turned off, but that'd just stink.