Beta 4.2.0: Paint tool: Overlap set to Add hangs with lots of points

While using the paint tool with Overlap set to Add, I observed that the performance degraded quickly with the number of points. As a test, I drew a number of ellipses that overlapped. At around 10 ellipses the operation was noticeably slower, the 11th took about a minute to complete, and the 12th never completed (force quit after 5+ minutes).

To recreate in a new 5E campaign:

1. Open a new image
2. Paint > Ellipse
3. Set Overlap to Add
4. Draw ellipses that overlap slightly and repeat. On my laptop, FGU locked up on about the 12th one. Example: Capture.jpg

FGU Beta v4.2.0