The bug we're speaking about is only about long format, spanned MTS clips. Your issue may be something else. I will say this - Mercur enabled card and RAM being available is not going to have much impact on AVCHD playback. The main influence on playback is actually the CPU.
This document goes over how to work with this footage -- http://helpx.adobe.com/premiere-pro/kb/audio-video-glitches-avchd.html