Why on earth is iMovie so slow for me?

When you import from a Go Pro, it is in h.264 codec. This is a highly compressed codec that is good for playback but not good for editing. You will get better results if you Optimize Media. This will convert the h.264 file to Apple Intermediate Codec.

Try right-clicking on your Go Pro clip in the Event, and select Optimize Media. After it finishes performance should be much better.

See this post for more on this. H.264 is a Group of Pictures compression just like AVCHD.

https://discussions.apple.com/docs/DOC-3941

dook808 wrote:

When I tried to optimize the video the options (full-original size, and large 960x540) are both greyed out, not letting me choose those options. Not sure why..

That means that the video is already optimized. To check this, right-click (or Control-click) on a clip in the Event and select Reveal in Finder from the pop-up menu. In Finder, double-click the file to open it in QuickTime. In QuickTime's menu select Window > Show Movie Inspector. In the Inspector, for Format it will show Apple Intermediate Codec if the clip has been optimized. Otherwise it will show H.264 (the format recorded by the GoPro).

John

dook808 wrote:

Makes sense. With that said what do I look at next? What's the issue preventing me from speeding up the videos? Outdated laptop?

Not sure! But 2 GB of memory seems low considering what you are trying to do. I also have a MacBook Pro - it's listed as a late 2008 model, although it's processor was updated in March 2009. I purchased it in June 2009 just after a new model was released (got it at a reduced price and preferred the specs of the older model). I upgraded the RAM to 8 GB later - that seemed to make a difference, particularly with background rendering in Final Cut Pro X.

Have you tried cutting back the speed to 1000% - perhaps that will run better. You could then export the project in Apple Intermediate Codec to preserve quality (Share > Export using QuickTime), then re-import to an Event, create a new project and increase the speed again to 1000%. Cumbersome and time consuming, but you are of course working with a 45 minute project! Both iMovie and your Mac has a lot of work to do to make the speed changes.

Sorry I can't offer other solutions. Perhaps AppleMan1958 has some further suggestions.

John

EDIT: The second time around you would need to increase the speed to 2 times (not 1000%), as that would effectively give you 2000% overall (unless I've messed up my Maths).

Message was edited by: John Cogdell

I wrote:

Cumbersome and time consuming, but you are of course working with a 45 minute project! Both iMovie and your Mac has a lot of work to do to make the speed changes.

Just re-read your initial post and noticed that you had done a test at 2000% on a short section and that failed as well. So, there may be another issue. I'll have a think and come back.

John

Message was edited by: John Cogdell

I've run a test on a 28 minute project. The video was imported as Large (960 x 540) optimized - so it's in Apple Intermediate Codec (AIC) format.

Rather than using the speed slider in the Inspector and typing in 2000%, I changed the speed by using the menu item "Clip > Fast Forward ⇒ 20x" (2000% is of course 20x). This worked instantly. The clip thumbnails were immediately shortened in the timeline (reflecting the faster speed) - I had them set at each thumbnail representing 2 seconds. Playback was instant also with no waiting whatsoever.

I also tested by using the speed adjustment in the Clip Inspector. Typing in 2000% in the box alongside the slider also worked flawlessly, with all clips (28 minutes) selected.

So, in my case, iMovie is working perfectly with speed changes, no matter which method I use. I'm not sure how it would go when Sharing (exporting) - perhaps rendering will take extra time due to the speed change.

My testing was done on Mountain Lion (Mac OS X 10.8.3) and iMovie '11. From your profile, you appear to be on Snow Leopard (10.6.8) - is this still correct? Also, what version of iMovie are you using?

You may need to trash iMovie's preference file. If so, follow these steps (I've included references to Lion and Mountain Lion for the benefit of other users on those systems):

Ensure that iMovie is closed.

In Finder, go to the folder <your user name>/Library/Preferences (where <your user name> is your Home folder). For users on Lion (10.7) or Mountain Lion (10.8), the Home Library folder is hidden. To access it, in the Finder menu bar click on Go while holding down the Option key.

For iMovie '11, in the Preferences folder locate the file named "com.apple.iMovieApp.plist" and drag this file to the Trash. For versions prior to iMovie '11 (currently version 9.0.8) the preference file has a slightly different name. For example, for iMovie '09 the file is named "com.apple.iMovie8.plist".

Open iMovie - a new preference file will be created with the default settings (this happens in the background while iMovie is loading).

If iMovie is now working OK, you can change the default preference settings as desired - click on iMovie's menu item "iMovie > Preferences" and make the desired changes for the relevant items in each of the tabs.

Hopefully this will fix your speed change problem - but no guarantees!

John

You would definitely get better performance from a new Mac.

If you need to get more usage out of your current Mac, I would consider increasing the memory to 8GB.

It is inexpensive relative to getting a new Mac, and it may help.

http://eshop.macsales.com/shop/memory/Apple_MacBook_MacBook_Pro/Upgrade/DDR3

The other thing to check is the free space on your hard drive. If your hard drive is getting full, it can really slow things up. Move some of the larger files to an external drive. Aim for 10% to 20% free space on the internal drive. The operating system needs this free space to function.

Great news! Thanks for letting us know. Keeping the operating system and all apps up-to-date seems to work for me (but we still get a few bugs here and there).

Have fun with iMovie '11 and Mountain Lion - you won't regret updating (unless you still use some legacy Power PC apps which don't work beyond Snow Leopard).

John

Thank you for the helpful tips. I have a slightly different problem and wonder if anyone can help.

I have also suffered from the slowness of iMovie, which I have been using almost since it first came out. Currently running ver 9.0.9 on a 2012 Macbook Air with 512 SSD and 8GB RAM. I have a lot of events and projects (roughly 250 GB), most of which I have moved to an external drive (within iMovie). So far, so good.

The slowness has been bugging me for a long time, and of course it hampers productivity quite a bit. From perusing various online discussions, I gather some people have seen improvement in iMovie performance by deleting the iMovie prefs file, so I tried that. iMovie then started very quickly and was very responsive. However, it would not see any of the events or projects on my external drive -- the drive was recognized but it just showed the yellow triangle with the exclamation point. Tried adding symlinks pointing to the external drive but that did not help. This was not a problem prior to deleting the prefs file. When I restored the old prefs file, the events and projects on the external drive show up normally and I can work with them sans problemo, except for the slowness.

Any thoughts?