Sorry I was not clear. Footage is on external G-RAID Mini drive via Firewire 800 connection. Even with no filters/transition etc. The playback stutters after about 15-20 minutes of program use (eg; during logging footage). If it were drive speed issue, the footage would stutter from the start and and problem would not clear up with a program restart.
It’s as if PP6.0.0 and PP6.0.1 has a caching/memory management problem with AVCHD footage. Problem specific to Nikon D4, D800 footage. (I am also aware to the old problem with PP5.5 requiring Nikon footage to be renamed from mov to mpg. Tried that too. same bug.)
I am a former Apple Certified FCP, also use AVID Symphony 6. Been editing for most of my life. Its not a rookie thing. 🙂
David