I have the same problem. I built quite a beast rendering machine recently and I'm experiencing the same problem. Hoping someone will give us some answers. I read through this forum, that might not give very good answers, but they talked about "unparking cores", not really sure how to do that, but it might be worth a shot. Also, I think sometimes I am limited because I have so much media on my external spinning drives that are USB 3.0, and when I check task manager, they are maxed at 100%. So if I had 4 TB of internal m.2SSD storage I could move everything over, but I only have 2 TB, but it has been a bottleneck for live playback.