Hey Chris,
You can try giving pix_texture a 'client_storage 1' message and see if that helps.
I tried this, but it doesn't improve the situation. The funny thing is that if I play it with [auto $1] the loop function works smoothly, but the playback stutters. If I make my own manual counter, the playback works smoothly, but making a loop gives me a freeze in the last/first frame.
Thanks a lot, Sara