Renderer Parallelization (CPU/GPU/RHI) messed up in 5.4.4?

According to Epic, UE5.4 was supposed to bring huge improvements in process parallelization as e.g. outlined here:

Funny enough, with the release of 5.4.4 the total opposite, i.e. an unbearably bad scenario unfolded for me: While the CPU and GPU do their work just fine, the RHI just sits and idles until GPU and CPU are done.

RHI only gets out of bed, once CPU and GPU are almost finished, forcing CPU and GPU to wait a staggering 9ms for the RHIT to finish, making the full frame render incredibly slow. WTF?

According to my observations, not everyone in our dev team is affected by this issue, but it is seemingly affecting members with a 3090 RTX (like me).

Before 5.4.4 process parallelization was a lot better on my PC, i.e. there actually was a parallelization, which now went totally bust and bricked my dev work.

Anyone else affected by this? Or any ideas what could be done to improve the situation? I already tried the obvious, like installing latest GPU drivers, rebuilding with VS, deleting temp files etc.