Premiere Pro 24 slow, when switching back to it in Windows 11

When returning back to Premiere Pro 24.1.  (running in background) on my Windows 11, it is slow and I have to wait 4-5 seconds until Premiere reacts/until I can play the preview.

Very special: I'm using a brand new Dell XPS, 64 GB Ram, Intel i7 13th Gen. with  Nvidia Gforce RTX 4060.

In the settings I set that Premiere may use 80% of the RAM..

Any ideas what could cause this?