Import to FCPX from AVCHD has recently become excruciatingly slow for unknown reasons

Sorry you're having trouble, but on the other hand, good to hear it is not just me. I find that importing any clip from AVCHD longer than about 15-20 minutes or so is extremely slow. For example, I have a 2-hour clip that I let import run overnight and it took over 4 hours to import! I have eliminated most variables, and have come to believe it must be a problem with the latest version of FCPX.

I have found a workaround that works for me until FCPX is fixed: I have been using the program "EditReady", which will re-wrap the AVCHD clips into .MOV files. It takes a little time to do, but it is reasonably fast since EditReady has an option to not do any transcoding but simply re-wrap. And it is way, way faster than FCPX import. Those .MOV files then import into FCPX very fast.

As the next experiment, installed a new copy of FCPX on the MacBook Pro I had, and tried importing a 1-hour clip from an AVCHD file. It was better, but still not great. Took 36 minutes to import that 1-hour clip. This laptop doesn't have much on it except Microsoft Office (which wasn't running), and no special codecs or anti-virus s/w. I don't understand why the MacPro takes twice as long, and why the MacBook takes as long as it does. Further adding to the confusion is that MacPro can import a 3-hour 4K file (MP4 H.264) in about 10 minutes. My conclusion would be that something has changed in FCPX that makes it really slow at importing large clips from AVCD files. But yet, Alchroma gets good performance. I'm stumped.

In the meantime I'm using "EditReady" to rewrap the AVCD clips as MOV files, and then they zip into FCPX really fast. The rewrapping by EditReady takes some time, but nowhere near as much time as FCPX does to import directly from the AVCHD, so it is a net gain. Annoying, though.

Importing from AVCHD always has the same symptom: The import starts out nice and fast, but gradually slows down until it is crawling. Short clips have no problems, they go right in. But long ones end up crawling for a long time. It is like some resource runs out, or some algorithm doesn't scale during the import. This didn't used to happen. I don't know what changed (other than possibly newer version of FCPX, I don't know exactly when this problem started in relation to recent upgrades).

All I know is that FCPX AVCHD import has recently become intolerably slow (I am not creating any optimized media). If I first simply convert the AVCHD to MOV clips using an external utility (that also does no transcoding), then FCPX will import just fine. It appears that FCPX has some sort of problem with the AVCHD format.

Tried removing AppleIntermediateCodec.component and AppleMPEG2Codec.component from /Library/QuickTime. Didn't make any difference.

I'm at a loss. The only thing I can think of to try next is, I have a MacBook Pro sitting around that is not normally used for editing. I can put FCPX on it and see how it does. To double-verify that it is something specific to this machine.

Our posts crossed, but I moved the AVCD file to the internal SSD, thus eliminating the HUB. See that post.

The disks are formatted Mac OS Extended (Journaled), which hasn't changed since back when this wasn't a problem.

The external drive being imported to has 8TB capacity, and only 1 TB has been used, leaving 7 TB available. It has a thunderbolt connection.

The external drive being imported from is an 8TB drive connected via USB 3.0 via USB 3.0 hub. Nothing else is active on that hub at the moment.

Since 4K files from another camera that doesn't use AVCHD import fine from and to the same disks, it wouldn't seem to be the disks. (The 4K files used to take longer to import than from AVCHD, now it is the other way around).

macOS High Sierra 10.13.5, 32 GB memory

Two AMD FirePro D700 GPU

Quad-Core Intel Xeon E5 3.7 GHz 4 cores

Internal drive is 1 TB SSD with 462 GB available

What else would you need to know?

Good to hear it is just me, and not some generic FCPX thing -- if only I could figure out what it is!

Thanks for the reply.

In attempt to eliminate the source disk, I copied the entire AVCHD file to the internal SSD drive, and tried importing from there. The OS didn't seem to have any trouble reading from the source disk, since it copied the entire AVCD file in about 7 minutes. I then imported a 30-minute clip from the internal SSD and it was done in a few minutes. Great I thought, but then I tried a 1 hr 18 minute clip from the same AVCHD. It zipped along importing until it reached about 20% and then hit a wall and slowed right down. Now importing only about 2% a minute, which would mean another 30 minutes to import that clip. It is like there is something that happens once the imported clip reaches a certain size. Now I'm wondering if there is something going on with writing to the library (destination) disk? But that doesn't explain why other imports of other formats with bigger and longer files don't seem to have the problem. This is confusing. I guess my next test will be to create an FCPX library on the internal SSD to eliminate both external disks (input and library). All I can think of.

I've never heard of Perian, and when I looked up instructions on how to uninstall it, it appears that I don't have it.

I also haven't heard of the A52 codec. When I look in /Library/QuickTime (which is where all the codecs are, correct?) it only lists the following:

AppleAVCIntraCodec

AppleHDVCodec

AppleIntermediateCodec

AppleMPEG2Codec

AppleMXFImport

AppleProResCodec

DVCPROHDCodec

FCP Uncompressed 422

IMXCodec

Yes, importing directly from SD card didn't make any difference.