in Pixelmator Pro 1.0.5 (PP1), if I am working on an image. The image is a near 4k image resolution. I try to use magnetic or color selection tools. Upon making first selection, PP1 goes into a death spiral. Its not completely unresponsive... it becomes terribly laggy. If you right click on dock icon, you see the option "Force Quit" instead of just "Quit". I can sometimes wait for it long enough and it becomes reasonably responsive again. However upon next edit, it repeats the before described lag behavior.
I am on a MacBook Pro 15" 2017; 3.1Ghz, 16GB RAM, Radeon560 4GB; 1TB SSD. I also have a Thunderbolt 3 connected eGPU Developer kit (Sonnet + Sapphire RadeOn RX580). I have not tried to disconnect the eGPU but given all other functions work well, not sure if its specifically eGPU or not.
Is something not working like it should? Let us know.