Tiny specs that can't be removed

Lightroom has recently been slow in editing for me. This was an abrupt change of speed. I have made some changes, per suggestions online, which seem to have sped things up a bit. However, now I have a new problem. Tiny specs have appeared all over my images. I often black out portions of my images, and I can't do this using any of the techniques I have used successfully in the past (e.g. brush, spot, filter tools). The tiny specs (whick look like pinpoint light spots) remain. Perhaps of importance, one of the 'solutions' I implemented in order to improve the initial speed issue was to create a new catalogue and re-import raw image data into that new catalogue. It is in this new catalogue that I'm seeing specs that aren't seen at all in the same images in the other catalogue. Any thoughts/suggestions?