Storyline 360 Running Very Slowly

Just ran into this same issue when building a critical project this weekend. Storyline 360 was running smoothly and I was building out a drag and drop interaction that involved importing 9 image files. I was in the process of using the built-in contrast adjustment filter when BAM...the tool throttled waaaaay back and took about 3-5 seconds to execute further mouse clicks. Deleting the whole slide fixed the problem, so I knew it was likely the images. Decided to apply the contrast filters, screenshot/saved the results I liked, deleted the images, and then imported the screenshots. This approach worked beautifully, and I am back up and running again. In my case, the application of the image contrast adjustment is what slowed down the application. Hopefully this info helps someone else down the road.