[Gareth Hoover]

I think the best workaround for this is to create separate video tracks with adjustment layers positioned over your video clips and apply the effects to them. For my 40 min film I used three separate tracks for color grading, sharpening and curves. This way you can just turn off individual tracks and run your previews smoothly. Of course, it does make your file bulkier but it’s a small price to pay.