I just used a custom pwnage ipsw to upgrade from 2.2 to 3.1.2. However, I noticed the phone is running much slower than before. Is there a way to fix it? I used recovery mode (DFU mode wouldn't work, error 10 when iTunes was verifying the iphone firmware).
You didn't backup from a restore after the custom firmware was installed right? This can cause issues. Set it up as new phone and just sync afterwards.