Hi,
That behavior is very strange and should not happen. LOG file would be very useful and we would like to get bottom of this. it is very possible that there is some memory leak during large conversion FLAC -> M4A and then sync, so it slows down after time.

I can't replicate on iPod Touch, thus I synced only 2000 tracks.

I made this final posting only so that, in the future, anyone seaching the forum who runs acrossed it knows how it turned out for me.

While trying to chase down this issue, I did discover that I had 37 non-music files scattered throughout my music directories. I also found 17 .m4a files that MM4 would play, but not sync, so I converted them to .mp3. However, correcting these issues didn't solve the problem.

Using MM4 to sync my iPod starts out normal, but randomly slows to where it takes several minutes to copy a single song and hours to complete. It doesn't matter if I sync 15 or 15,000 tracks. After completing a sync that slows down this way, MM4 corrupts iTunes on the iPod. The iPod shows no music even though it's all actually still there. The iPod then can't be read by iTunes on the PC and I have to reset it back to factory and start all over again.

After spending over 40 hrs. on this issue, I finally give up trying to sync my iPod using MM4. I ended up using MM to convert all my .flac to .mp3., then did a complete load of everything into iTunes. iTunes will repeatedly sync my iPod with almost 15k of very high bitrate mp3 tracks in about 3 hrs. without errors.

This isn't the solution I had hoped for as I really like MM, but I'm not going to keep wasting this much time when I want to sync my iPod Classics. Going forward, I'll only use MM to manage my music library and play music at my computer or over my home network.

Nothing, leave as is and save log once you're done capturing.

Thank you. I'll do that as soon as the one I'm running now finally finishes, probably some time tomorrow.

What Dbgview options do I set to capture what the developers need ?

I suggest capturing it in a debug log (step 4b) and attaching the log to a Support Ticket: https://www.mediamonkey.com/forum/viewt ... ?f=12&t=69

You probably don't have to capture the whole day long sync, instead from connecting to the device to where sync seems slow may be enough for developers.

I've struggled to get my iPod Classics to sync ever since upgrading from MM3 Gold to 4 Gold Lifetime. It's only gotten worse as I've continued to keep MM upgraded to the most current version, now 4.1.21.1875. It can take days to sync once I load more than 10,000 songs. Yesterday, it took 16 hrs. to sync 259 songs. Since last night, MM4 has only been able to sync 162 songs in 11 hrs. If I could get MM to sync my entire library again, I'd still have about 1/3 free space on each iPod.

I used to think that MM4 locked up, so I'd terminate it from the progress bar which then corrupted iTunes on the iPod. My only option for recovery was to reset the iPod to iTunes 2.0.4 and start syncing everything again in small batches. Now I've discovered that MM4 has just slowed down processing. I have to let it finish syncing, no matter how long it takes, to keep MM from corrupting the iPod. It can take up to an hour to copy a single mp3.

I've scanned and tested all the disks in the iPods and PC. I've tried rebooting my PC between every sync. I've tried syncing with Windows in Safe Mode with Networking. I've rebuilt my MM library from scratch. I can find nothing wrong with any of the files in my MM library as they play fine in MM and other media rendering software. The vast majority of my music files were in my library before upgrading to MM4.

My MM library currently contains approximately 13,000 mp3 and 3,000 FLAC files which I convert during sync. The one thing I haven't yet tried is to sync only the mp3 files.