It is caused by the codec and especially by the compression and algorithms used to decode the material. EX3 is a lot easier on the system.
Thanks for that. Any ideas on how to get around this?
Probably the best enhancements would be a faster CPU and a faster I/O sub-system. With non-AVCHD material, the latter will likely have the biggest impact. For AVCHD, the former will.
Can you tell us all about your I/O sub-system, i.e. your HDD's, their size, speed, controller type, free space and how you have them allocated?