When I first start working in a project, when I scrub through a sequence it is extremely responsive, with no apparent delay or lag. After about 15min the scrubbing starts to become sluggish, where the playhead has trouble keeping up when I drag it.
I’ve found that when I simply duplicate the sequence, without making any changes at all, that new sequence scrubs responsively again. After 15min it again becomes sluggish and I can repeat the process to maintain responsiveness. I can also make the performance responsive again by quitting Premiere and opening it again. Obviously neither solution is ideal.
As for tech specs I am on a 2022 Macbook Pro 16in, M1 Max, 64GB RAM, Mac OS 12.6, latest version of PR. I am editing 4k ProRes footage off of an external SanDisk Extreme Pro SSD connected via USB C (or Thunderbolt? I can’t tell the difference).