Mac Pro 7.1 + Radeon Pro W5700X: drop of graphics performance

I just replaced my Radeon 580X MPX with the new Radeon W5700X MPX graphics card.

Unfortunately I noticed an occasional drop in graphics performance in macOS 10.15.4, especially after wake-up from sleep. Geekbench5 Metal score drops in this case from about 70.000 to 40.000 and lower. Same for gaming, FPS drops from above 80 to below 10 FPS. The issue occurs with W5700X as single card or installed in parallel to the 580X.

The only workaround I found so far is to install macOS 10.15.5. Public Beta 2. With this Beta the graphics performance seams to be steady so far.

Using the card in Win 10 with Radeon Bootcamp drivers 19.40 the behavior is similar. Occasionally the graphics performance drops as well (GeekBench5 Vulkan from about 56.000 to below 20.000). So far mainly when card is installed as primary card beside the 580X. No workaround found yet.

Does anyone noticed similar issues and found a solutions already? I assume it‘s on Apple and AMD to provide stabile drivers. Hope someone is reading here.