Can you try to limit Number Of CPU cores that are used in MM Tools -> Options -> General -> Performance

I am having this same problem. I tried changing the temporary directory, but it is still very slow. Please help us find a solution.

My disk is defragmented completely and there is lots of unused space >50%.

After updating all FLAC tags the problem (slow and disc grinding) persists.

I also tried converting all my FLAC files to AAC and M4A. Same problem while converting.

I wonder if it is the converting from FLAC or converting to AAC/M4A that is the problem?

if MM has to update flac tags and there is insufficient space with the existing tags (called padding), the whole file has to be re-written. Typically this has to be done once, as MM will leave extra space when it updates the tags (adds padding).

You can test this by updating some flac a second time and see if it updates much faster.

It also could be a disk fragmentation or speed issue, as flac files are larger, they take longer to read/write then mp3 or other smaller files.

Could your files be extremely fragmented?

I've recently added a large number of FLAC formatted songs to my library. I have found that processing these files is very slow.
For instance, if I select a large number, say 100, flac files and request volume analysis many (around 20) are quickly analyzed, then my hard drive starts grinding wildly and analysis starts taking many seconds per song. I get a similar problem when auto-converting when synchronizing to my iPod (converting to AAC).

Because of the grinding of my hard drive, I am assuming that there is a lot of data being read and written to my hard drive. I thought I might resolve this by moving the temporary folder to another drive. However, this did not help; in fact the temporary folder isn't being used.

Is this a normal problem? How can I fix?