Lag in timeline when changing speed of clips

JIm's got a good basic bit of advice especially for that media. Which is undoubtedly long-GOP. That means there's a complete frame every 9-30 frames( i frames ), and in between there are data sets for the pixels that 1) have changed since the last i-frame, 2) will change before the next i-frame (requiring of course that i-frame to be decompressed and decoded plus stored to RAM and recalled for every involved frame) ... or both.

It's incredibly CPU/cores/RAM intensive work. Throw in an NLE's heavy demands on the computer along with it, well .. it's difficult. Which is why making Cineform intraframe proxies works better for playback. Every frame is complete just compressed ... far easier on the computer to play, even though at times the files are bigger than the original media.

Cutting resolution refers to the little item in the lower right corner of the Playback Monitor, where you have the option in drop-downs for Full, 1/2, 1/4, or 1/8th resolution. This can help playback also.

Running that media with warp stabilizer applied can be rough on a computer. Two very heavy processes ... just reading & prepping the media for playback, THEN ... before playing back, applying the complex shifting warp process to it. Sometimes it's wise to run warp on clips, then export that to a 'digital intermediate' codec like Cineform, DNxHD/R or ProRes (later if on Mac only), re-importing that into the project, and using that on the sequence rather than the original clip media.

Especially if you've got other heavy lifting like color correction or video noise reduction to be applied later.

Neil

Hey there, sorry for the delayed reply, I haven't been getting email notifications from the forum.

Optical Flow will actually create new frames, which is why it's such a render-intensive effect. If you feel that it gives you the best results, then by all means, use it. You just need to render the clip first. Even on a powerful machine I still speed change clips with Optical Flow.