when you are overclocked everything is a little quicker. The delay in 6.5 you are talking about.. is that the delayed flip? This was something that was put into the 6.5 rom on purpose, so you would see it flip.
You can install the disable flip cab that will stop that.
Link here -
http://forum.ppcgeeks.com/showpost.p...78&postcount=3
The CHT mod has it as a built in option too.
Link to CHT here -
http://forum.xda-developers.com/showthread.php?t=625483