If you are experiencing slow or laggy masking or brushing performance with ON1 Photo RAW 2019 when using the brush or masking tools, we would recommend the following:
1. If you are running ON1 Photo RAW 2019 on the Windows OS, please make sure your GPU driver has been updated and also make sure that ON1 PHOTO RAW 2019 is properly configured to run off the the GPU: Follow the steps in this article.
(Please note, that if a Windows update occurs, this can reset the GPU settings, so you'll want to make sure the app is once again set to run off the dedicated GPU)
2. Adjust the size of the program window to be smaller than your display size.
3. Prior to doing any masking or brushing - turn off or disable all other filters or local adjustments in your stack other than the one you're are working on.
4. Close the Presets/Filters panes on left hand side, so that only the list is showing (and not thumbnails)
5. Disconnect your tablet and/or external display prior to launching ON1 Photo RAW 2019 and editing/masking.