I have run some test on different machines to determine the performance of Awesomium.
We all know the performence is poor especially in fullscreen, but there is more to it than that.
I have testet my game on these two machines:
AMD e300 with integrated GPU and a very slow cpu.
Intel i5 2500k + GeForce 560ti
Both machines run the game in fullscreen 1920x1080 with about 12-15 fps and 1280x800 with 35-40 fps!
Judging from this, it is clear that there is some kind of bug in Awesomium and that is not related to the performance of the CPU or GPU - but rather some kind of software bottleneck.
Please make your own tests with different resolutions on different machines to confirm this bug.
I'll write to the Awesomium team about this.