@1% - Just noticed something strange. With the same settings (1120x400) and shooting exactly the same scene, I'm getting 109 frames on one shot then 145 on the next, then it goes back to 109, then 145, 109, 145 etc.. a predictable pattern (Edmac Popin).
Other resolutions I've tried so far...
1120x434 it's either 101 or 134 frames
960x540 either 94 or 125 frames