The new Paint Brush Tool allows you to create custom brush strokes. When I use it, the more I use it in a document, the worse/slower the playback of my animation gets. I used to think it was because I was on a 2012 MacBook Pro with limited power/speed but I now have a VERY fast gaming PC with a GeForce 1080 video card and I recently experienced the same thing using the Paint Brush tool on a rotoscope animation. After about 20 keyframes with a few strokes each frame, the frame rate during playback (inside Animate CC) drops from 24fps to about 7. I have to use Edit Multiple Frames to select and convert the brush strokes to fills. When I do that, the frame rate is back up to 24fps. It's a bummer because for some reason, the new brush strokes are a huge memory hog on the fastest of machines.
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