Spot removal and brushing are known to slow down Lightroom if you do a lot of this on a photo.
Some things you can try
- Use Photoshop or Photoshop Elements for spot removal and brushing
- If you're going to do this in Lightroom, turn off the GPU acceleration
- If you're going to do this in Lightroom, don't do any lens corrections until you are finished with brushing and spot removal
- If you're going to do this in Lightroom, get a faster CPU
Forgive me what is a GPU accelerator/acceleration?
It's a new feature in Lightroom 6/Lightroom CC that uses the GPU to do some calculations in the develop module. It speeds up some parts of the develop module, and slows down other parts (like brushing and spot healing)
Found it...will give it a try. Thanks so much dj!