While scrolling a long document by dragging the minimap (as a scroll handle) while not showing entire map, there is a minimap refresh problem (flashing and updating very slowly) while lines 1000-1050 are displayed in the main edit window. Before line 1000 and after line 1050, it works beautifully.
Update. Loaded a longer file and it also happens while line 2000-2050 are displayed in the main edit window. Cut and pasted my document to the end of itself to make it even longer for testing and it appears to repeat every 1000 lines.