[I'm copying this over from the COW thread:] I may have found something... I was about to take my machine in to Apple for service, but before doing so I thought I'd try running Premiere in a 'clean' use account. So I made a new (admin) account, copied over some project files, and launched Premiere I set the project to CUDA, started 'working', and immediately noticed some differences: playback would start much faster, rendering started faster, less jerkiness in playback. And I was not getting any of the glitchiness. I had other issues besides the glitchiness, like clips dropped in dynamically from Ae would not update unless I manually switched over to Ae, and these things went away. I didn't really spend several hours actually working, but it seems much smoother. Made me think the issue was due to 'gunked up' settings etc over months of work. So I (backed up and) wiped my drive, clean installed Yosemite (I was on Mavericks before), set up CC etc. But after copying over all my settings, including downloading settings from Adobe, the performance was twitchy again. Bummer. I created a fresh account again, and again, in the new account, Premiere performed much better. Even complex speed ramps and Ae clips played back incredibly fast in real time, better than I've seen in months. I won't know for sure until I spend a day editing, but it might be that a lot of these issues stem from corruption or some kind in the user settings. So I went back to my original account, and deleted EVERYTHING with the word 'adobe' or 'premiere' within my User folder (including ~/Library and ~/Documents). The performance is now similar to that of the 'clean' account. So far it's working rather well ... I will report back after spending more time. Maybe some other can test this out and report back ... try a fresh account, and if you notice a difference, go back to your main account and delete (or put aside) all the Adobe stuff in your ~ folder. DO NOT SYNC SETTINGS from Adobe servers. If, like me, you absolutely need your custom keyboard shortcuts, you can manually copy the .kys files from ~/Documents/Adobe/Premiere Pro/8.0/Profile-CreativeCloud/Mac/
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