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The version of iMovie I’m using with this machine — iMovie 10.1.10 — has become incredibly slow when rendering 720 videos

Right …


I updated my 2017 model 21” iMac, on Thursday: as the security components of the Mojave 10.14.3 update seemed rather important.


Ever since then, the version of iMovie I’m using with this machine — iMovie 10.1.10 — has become incredibly slow when rendering 720 videos.


To the point where I’ve tweeted Tim Cook about it: I’m THAT annoyed.


I’d like to ask a couple of questions.


Is anyone else getting the same problem?


If they are, how are they coping with it?


[Edited by Host]

iMac Line (2012 and Later)

Posted on Jan 26, 2019 3:17 PM

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Posted on Jan 27, 2019 5:38 PM

Try deleting preferences by restarting your computer and opening iMovie while holding down the Option and Command keys and selecting to delete preferences in the box that appears. iMovie will open in a new library. Reopen your old library to get back to your projects. Now see if the issue is solved.


If that doesn't work, try booting up in Safe Mode (see help menu for instructions) and, after everything loads, immediately shut down and reboot in normal mode. Sometimes that clears out conflicts.


To rule out a conflict with your main user account, you also can try opening iMovie in a new user account such as the Guest account on your Mac, or another user account. Then see if the issue is resolved.


Finally, if you share out in Best Quality (pro res) setting, your file size will be 4x larger and thus slower to render. Also, confirm that the "Add to Theater" box is not checked when sharing out. Sharing to Theater greatly increases rendering time because Theater uses multiple formats to make the movie playable on various devices.


-- Rich

9 replies
Question marked as Top-ranking reply

Jan 27, 2019 5:38 PM in response to Paul Downie

Try deleting preferences by restarting your computer and opening iMovie while holding down the Option and Command keys and selecting to delete preferences in the box that appears. iMovie will open in a new library. Reopen your old library to get back to your projects. Now see if the issue is solved.


If that doesn't work, try booting up in Safe Mode (see help menu for instructions) and, after everything loads, immediately shut down and reboot in normal mode. Sometimes that clears out conflicts.


To rule out a conflict with your main user account, you also can try opening iMovie in a new user account such as the Guest account on your Mac, or another user account. Then see if the issue is resolved.


Finally, if you share out in Best Quality (pro res) setting, your file size will be 4x larger and thus slower to render. Also, confirm that the "Add to Theater" box is not checked when sharing out. Sharing to Theater greatly increases rendering time because Theater uses multiple formats to make the movie playable on various devices.


-- Rich

Jan 27, 2019 11:31 AM in response to IanDLBZF

Depends on how I do it.


Under these conditions, if I forceable power off my Mac, then turn it back on, I get a message that tells me the video’s been successfully exported to my desktop.


If I don’t … ?


A 20 second movies takes about 20 minutes to export.


I take it you’re getting the same problem, exporting something to YouTube, from iMovie … ?


Jan 30, 2019 7:30 AM in response to Paul Downie

I would repost your question in a new thread, refer to this thread and tell what helped. That would re-expose your issue to the entire community for further comment. If the issue is prevalent perhaps someone has found a permanent solution. I take it that you have tried Safe Mode and opening in a new user account as I mentioned in my earlier post.


-- Rich

The version of iMovie I’m using with this machine — iMovie 10.1.10 — has become incredibly slow when rendering 720 videos

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