15 seconds of spinning ball before a project will play?

Hi Guys
I really don't know whats going on here.
Ive got the top of the range iMac Retina 27" (Completely top of the range)

I'm currently working with a 1080p project that I would NOT class as heavy going (3 angles in a multicam clip and a bit of b-roll on top).
Running from USB 3.0 external hard drive.
Whenever I goto start my project to play it through I get the spinning ball for 15 seconds, then it stutters for a bit, then it becomes OK...Try to start it again, hit play again...same thing happens again.

It doesnt matter if I'm using proxy media or not.
I dont know if its come from updating to 10.2.2 very recently or not (I cant see how it would have done) as Ive not got this issue with any other projects sitting on the same USB3 external hard drive.

Ive tried turning off every effect, text etc and nothing. Its still runs terribly.
It still runs badly when I go into the (all lined up clips of the) multicam clip on one line, out of that into the final compound clip.

I have noticed that although (I'm sure) I set the project to 25p (2 camera angles are 25p and one is 30p) I seem to have accidentally set my multicam clip at 30p and my final compound clip at 30p.

But surely my system should still be able to handle this OK?

In fact it was completely fine for editing (I was very nearly done) and was very smooth until this happened.

Ive tried using "Preference Manager" to trash all the settings but thats not helped.

Any help anyone?
Thanks in advance

iMac, OS X Yosemite (10.10.4), 27" Ret 32GB Ram 4GB Graph 1TB SSD

Hey Coffee King, have you tried remaking the multicam clip in a new Library to make sure there's nothing corrupt about the existing one?

You could also conform the 30p file to 25 in compressor and recreate the multicam to eliminate that as a problem.

The USB 3 drives is still going to max out at the physical drive speed of ~120Mb/sec. What's the bitrate/codec of the footage?

don't miss my reply in your post at ASC
discussions.apple.com/message/29589373#29589373

coffee_king wrote: ...It doesnt matter if I'm using proxy media or not....

This may sound obvious, but when you transcoded to proxy did you afterward switch the viewer to proxy? If not it's not using the proxy files.

Also, is the USB drive a bus-powered 5400 rpm portable drive or is it an AC-powered 7200 rpm drive? There can be huge performance differences between a slower bus-powered 2.5" USB 3 drive and a fast AC-powered 3.5" drive.

coffee_king wrote: ...it was completely fine for editing (I was very nearly done) and was very smooth until this happened...

This is more mysterious -- it implies the hardware and software were capable of the task, then something suddenly degraded or became unstable. It is possible you accidentally bumped the viewer from proxy back to original? Can you delete all the generated library files and rebuild them (cache, render, proxy, etc)?

Is it possible your hard drive or system drive filled up? I suggest checking the available space, then running a BlackMagic disk test on each of your drives to verify they are producing the expected performance.

Hi Joema
With regards to Proxy Media
Yes, Ive switched back and forth and it doesnt make any difference.
TBH I dont really ever need to use Proxy media with this iMac.

The Ext Hard drive is not the issue as again I have other libraries on there working perfectly fine that are MUCH more complex that this.

Ext Hard drive space 2.2TB free from a 3TB drive.

How do I delete generated library files and rebuild them without loosing all my edits?

Thanks in advance.

Are there any re-timed clips in your project?

also support.apple.com/kb/PH12704?locale=en_US

coffee_king wrote: ...
How do I delete generated library files and rebuild them without loosing all my edits?...

There are three ways:

(1) In FCPX, select Library, the Files>Delete Generated Library Files, click all the check boxes, then rebuild your proxy files.

(2) Use Final Cut Library Manager: www.arcticwhiteness.com/finalcutlibrarymanager/

(3) Use X-Wiper: itunes.apple.com/us/app/x-wiper/id761443168?mt=12

For more details see MacBreak Studio episode #272, starting at 09:30:

Hi
Ive followed all the steps on here
support.apple.com/kb/PH12704?locale=en_US
but still no luck I'm afraid.

There must be something seriously wrong with this project as I cant even get it to play right with all effects, transforms, crop. distorts etc turned off.

At this point my advice would be make a new library and copy (not move) the projects, clips and events there. I suggest you not copy proxy or optimized media, but rebuild those in the new library. Afterward see if it behaves any better.

support.apple.com/kb/PH12766?locale=en_US

You seem to have plenty of hard disk space, so you could also consolidate media to the new library to ensure even the media is duplicated. Otherwise for non-managed media, FCPX only duplicates the symbolic links, not the actual media.

If it still behaves similarly in the new library, you have a complete copy of your library and you can start backing out changes or selectively deleting items to try and isolate where the problem is.

I only suggest these steps provisionally, in lieu of advice from others.