I'm getting about 50 FPS with 250 Fish, but I'm seeing the same behavior you are Daniel; I'm seeing my
CPU temp spike way up, but my GPU is barely ruffled. They've got to be making SOME use of the GPU, but I think it's relatively basic.
For reference, FF 14, Fedora 17, Intel? Core™ i7
CPU M 640 @ 2.80GHz (two cores + HT)