I'd recommend a system clean up and a fresh installation of our latest Crimson 16.7.3 drivers, to see if it resolves your performance issues.
1. Run the Windows self check tool to check scan and automatically repair any corrupt files found in Windows. There is a guide on how to do it here. What you need to do is run an elevated command prompt (elevated means run it as administrator) and type SFC /SCANNOW. This will generate a statement indicating if errors were found the Operating system and if they were fixable.
3. Update Windows. Install all available critical, recommended and optional updates. Often Netframework and Visual C are included in the recommended or optional updates Windows provides. Windows should always be fully up to date before installing our drivers!
4. Use DDU to sweep the system of AMD drivers in safe mode.
5. Install the latest Crimson 16.7.3 drivers once the above is completed and check to see if the issue is resolved.
Nope. Still not working. Done all 5 steps. Inlcuding Downloads and repairing.
Lets check your temperatures. Use HWINFO64 to monitor the CPU Package temperatures. Download HWINFO 64 http://www.hwinfo.com/download.php
If the CPU package temperature gets up to around 65-70c, then the Motherboard VRMS could be overheating, this will cause the CPU to drop to the lowest clock speed momentarily and could cause the low performance. You can measure the temperature and CPU frequency using HWINFO.