Another thing which you might want to turn off in moi.ini for heavier files is:

[Drawing Aids]
<....>
ObjectSnapShowMarkers=n

That will disable the little "x" marks that show the available snaps around the mouse cursor. If you are working zoomed out on a heavy file there can be quite a lot of these getting drawn and it also needs to compute their visibility if View > "Display hidden lines" is off.

- Michael