(In reply to Kai from comment #15)
> On the upside: the FPS graph shown with radeonsi looks way more stable than
> the one I've seen with fglrx (like saw teeth), though that might just be due
> to the shaders not executed so far. With the stack detailed below, I also
> managed to get to > 60 FPS in some parts of the benchmark, while I barely
> saw 40 with the stack from comment #0. On the other hand, I'm still seeing
> drops to single digit frame rates (just above 3 FPS).

Sorry about the reported FPS increase to 60+: the game settings had dropped (I
have no idea why, I didn't change them). It's still better than before with the
current stack, but not so much, that I would mention it.