16” MBP M1 MAX SLOW PERFORMANCE

So I purchased the 16” Macbook Pro M1 MAX Specifically for the reviews about how incredibly fast it renders and edits video

I can’t even begin to explain how horrible the experience has been. Apple sent me a replacement computer but I am experiencing the exact same issues and can’t work out what the issue is.

FCPX is maxing out my CPU with 147%

while working on one project that’s approx. 10minutes long using 4K Iphone footage. There are no colour grades / effects / titles being used yet.

My library is saved onto a hard drive which I am directly working off. I’m also editing with proxy footage yet the playback is laggy. The spinning wheel of death appears every few minutes when I’m either trying to drag footage into the timeline, scroll through the content library or even when selecting a few clips and trying to turn down the volume on them.

I don’t understand how my 27” Imac 2020 with lower specs can handle my editing completely fine and this brand new MBP is struggling with 1 project. Apple has run all the tests possible and have yet to provide me with any solutions. I don’t know if I should just purchase an older laptop with the intel chip? These older models seem to be performing better than these new ones.