MTS/AVCHD - Jerky playback & super slow render? CS6

Hello

I recently shot a bunch of stuff on a Sony FS100. I used clipwrap to rewrap the 'private' file, using the setting 'don't alter video samples'.

Imported all into Premiere CS6. When trying to scrub through rushes, I can hardly view it becuase it's juddering and stuttering all over the place.

Same happens on the timeline until I render it out, which takes an age.

I've actually given up for now and had to convert it all to ProRes, and taken it all into FCP7 which is working a treat.

I love PP CS6, but this is a major ball ache... can anyone shed any light?

Thanks

Alex