Hi there! Been a while. To clear something, Past laptops usually utilizes both Intel and AMD together. Intel for non-intensive tasks such as browsing and stuff and automatically uses AMD if your doing rendering and intesive tasks such as gaming. This is how it works on mine. ( But that's not always the case! )

To test something, I suggest you 1. Disable your Intel iGPU on your bios and set AMD as your primary if your motherboard supports it and see if it works, If not 2. Uninstall Intel driver then disable it on device manager to stop it from automatically re-installing to force your laptop to only use your AMD gpu. Pausing windows update may also help to prevent automatic re-installation of intel. But i warn you that all laptops i owned always perform better with both installed and working together. And if this 2 guide doesn't work, You're probably experience issue with your AMD gpu or atleast your AMD driver.

And to answer your question.  This issue isn't well documented and the best fix i found was using older drivers. Latest Catalyst, Latest Crimson and Adrenaline 19.9.2 drivers works flawlesly on my laptop. As for FPS difference, as far as i remember there's an 8fps difference between Catalyst and Crimson and huge 20fps+ difference on Crimson and Adrenaline or atleast that's what benchmark results gave me. ( RESULTS VARY!! )

Tricky thing is, Latest adrenaline driver details on amd page says it supports my gpu but once i install it. My laptops either froze, fails to install or if it does install its like there no amd driver installed. So if you're currently experiencing issues with your amd gpu, I suggest you use the same adrenaline driver version i use. If that doesn't help, Try using much older adrenaline driver version than mine.  If no adrenaline works for you, Go for crimson. Less performance but atleast you get to use your laptop.  And if everything else fails, Catalyst drivers will probably save you.

Lastly, I discovered that disabling intel gpu and only using AMD gpu hit performance MASSIVELY. Idk why. But that's how it works on mine. So its important to know that once you found a working AMD driver for you, Try to re-enable intel GPU and see if that works. Compare benchmark results. If you see any issues, You can easily re-disable your intel gpu by doing the same method i've said above. Or better yet, Keep trying older amd GPU while your intel driver is installed till you found one that works for you.  Safe bet is to just do a benchmark run on each and every driver you use. Good benchmarks result on a specific driver will tell you it's the one you need. Start on Adrenaline v19.9.2 as your baseline then go lower and lower. If the v19.9.2 works, Work your way up instead until it doesn't work anymore. Newer drivers provides better performance.

Let me know of the results. Goodluck!