The AMD Gaming Evolved app is obsolete. Many of its features are now standard in the AMD driver software.
I think you should try resetting the shader cache in the AMD settings. To do this, right click your desktop and go to AMD Radeon Settings, go to 'gaming', then 'global settings' and in the top right click 'reset'. Then reset the shader cache.
The long load times may be caused by Mantle. I recommend playing on DirectX 11 at all times. Note that this setting only has effect after restarting the game.
If nothing works, a clean installation the graphics driver is also recommended. Use DDU to wipe the current driver, then install the latest driver from the AMD website.
