C1 ver 21 Slow

The C1 v21 release notes say:

(https://support.captureone.com/hc/en-us/articles/4408834421137-Capture-One-21-14-4-1-release-notes)

"4k / 5k monitors
Due to the significant additional calculation overhead, systems using 4k/5k monitors will require additional resources in addition to the above-recommended spec (both in GPU and CPU power). For professional experience, we recommend at least doubling the specification above for these configurations. "

Maybe this is why my 2018 iMac 5K is so slow?