I noticed that when you have the Crop autofocus frames by X % set in the AF options, SGP will still download the whole frame from the camera. Changing this option to download only the cropped frame would give an additional place to optimize AF speed in addition to increasing binning.
Additionally I think that the crop value (%) is a bit misleading, the first time I tried this feature I wanted to halve the frame size and entered 50 as the value. But this crops the frame 50% from both directions, resulting in detection area of 0 pixels and me wondering why the AF doesn’t catch any stars :). If you’re not keen on changing the established setting, maybe cap it to 45% or so to make the error more obvious?