My DDR5 (CUDIMM) is extreme tuned and very fast at DDR5-9000 (Gear2). I can run at DDR5-9200 (Gear4), but slightly slower since Gear4 adds more latency. What you are seeing is a well-known issue with latency in the memory controller in the latest gen Arrow Lake Intel processors. I have a massive amount of DDR bandwidth due to the speed and posted this in an earlier thread since I was one of the first here with a 285k Arrow Lake processor.
We had actually discussed this earlier:
