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FCP 7 performance troubleshooting – thread count.
So this is an odd one.
We have two iMacs with FCP 7.0.2 installed, both on 10.6.8. We’ve been using the gruntier one (2.8 GHz Intel Core i5, 4 GB 1333 MHz RAM) for editing.
Recently we’ve been having major performance issues when scrolling timelines with picture lagging, freezing, no picture coming up, just a green image.
After doing a set of standard troubleshooting things (free up disc space, delete cache files, trash preferences, copy sequences into new projects, check different projects), we decided to test head to head against the other iMac (2.66 GHz Intel Core 2 Duo, 4 GB 1067 MHz), and found we couldn’t replicate the problem on the slower machine.
The main piece of objective data that we’ve found is in the Activity Monitor. Looking at the thread count on the problematic machine, scrolling a couple sequences increases the open thread count to 70+ quickly, and they tend not to recede. (Once the thread count gets above 100 is where things really start freaking out.) On the working machine, it’s impossible to get the open thread count above 40 with the same behavior, and the thread count recedes quickly.
Has anyone seen this, and does anyone have any suggestions for things I might look at? The only other difference between the two machines is that the bad one has a couple plugins installed (Magic Bullet and Neat Video) but that doesn’t seem like this should account for this sort of behavior.