I'm using version 22.6 with multi-frame rendering enabled and it only uses a few threads and is really slow. Rarely it jumps to 100% cpu usage on certain frames, but everyone other time it's around 20-50%, but mainly around 25%. This is on multiple projects so it's not a project issue.
My basic specs: 12600k, 1050ti, 64gb ddr4 ram.
Does anyone know what might cause this? I've reinstalled the program and that hasn't solved the issue.
Without any info about your project(s) and the contents, critical settings like disk cache and hardware acceleration, actual render settings and so on this is not going anywhere. You need to be much more specifc. MFR is not a kudgel you can beat over AE's head to make it render fast. Other factors like file I/O, GPU acceleration and ultimately what effects and features you use still matter and some of those simply are limited to chugging along linearly on a handful of threads. The existance of MFR does not eliminate limitations that have existed in AE for decades.
Temporal effects like force motion blur always cause AE to revert to throttle down. It's an ages old limitation in how many threads those effects can use and how AE needs to process them linearly for correct results. Just removing this might drastically increase render speed.