I've recently been using a combination of mods that made the AMD issue painfully obvious, and for a pretty specific case. Maybe this helps to troubleshoot it or to find settings and tweaks to make the game playable for us AMD folks.
When a lot of fighters are in combat
and the Dassault-Mikoyan Normandy carrier ship system is enabled, FPS suddenly tanks into the single digits
like so. Observe twice the FPS
once the glows disappear. This happens whether fighters are on-screen or off-screen. I'm thinking it has something to do with drawing glow on many items. Not the complexity of it but simply adding up the numbers. The card can handle expensive stuff like GraphicsLib shader ripples just fine - I generally play with GraphicsLib loaded but shaders off.
This is not a mod issue. These mods just showcase it.Is there a way to disable special effects, or even any kind of lighting, on fighters and missiles in vanilla? If not, that would be a useful setting to have to fix AMD gripes in lieu of a better driver that likely will never come.