Thank you for the video. I was able to reproduce a problem, and have filed a bug. Here's what I see: When the Levels effect is applied to an adjustment layer after the Bilateral Blur effect, rendering updates to the composition preview is very, very slow. Even unrelated changes, like turning off the layer visibility, are not rendered quickly. It takes a long time (at least several seconds, much slower than the Levels or Bilateral Blur effects individually), and there is no indication in the Composition panel that After Effects is processing the rendered preview. It's possible other effects could also cause this condition. I tested a handful, but the only one that behaved the same way was the Smart Blur effect. I don't know what Bilateral Blur and Smart Blur have in common. This problem only occurs when the Levels effect comes after the Bilateral Blur effect on an adjustment layer. When they are applied to a footage layer or solid, etc., the problem doesn't occur. Masks or track mattes don't appear to affect the problem. I have a couple of workarounds to suggest: First is simply to wait for rendering the preview to complete. Not a great solution, but in my tests the rendering does always complete. Second is to avoid using an adjustment layer. In the video, what you show can be accomplished on one layer. Instead of duplicating the layer and making a track matte with a masked version of the layer, apply the effects and mask to the first, original layer. Then twirl open the effects in the Timeline panel and click the + (plus) button next to Compositing Options section of each effect to add the mask to the effects. (Note that you will want the mask in Add mode for this to limit the scope of the effects to the mask. The rest of the layer will not be masked in this case.)
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