Hi there. Hopefully you're not pissing it off too bad 🙂 It probably would take it out on me!
I just dragged over my Various Artists folder which loaded 4130 tracks. I added a bunch of other tracks which got it up to 6209. I did a Command-A to select all the files and Yate froze for about 5 seconds while it accumulated all the data. I then right clicked and selected 'link to iTunes' which took about a minute during which time the UI was responsive.
I'm assuming that you have already loaded your 6k files and then somehow selected them all at which point you are seeing a freeze before the files get selected? The freeze should end after a few seconds. If it does not then something strange is happening and we'll have to look deeper. Unfortunately this will involve narrowing down what is selected. Each time you change the file selection in Yate it has to recalculate the set of values which get displayed in the editing panels.
While we do have users that edit their tracks by the 'load 'er all up method' I personally prefer the smaller loaded set is better method. (and believe me I've edited my personal 40k tracks hundreds of times).
The linkage to iTunes is transient and only lasts while the files are open in Yate. There is no benefit to loading thousands of tracks at the same time unless there is common editing to be done over all the tracks.
Loading an album at a time gives you more granularity and there is far less chance to inadvertently mess up tracks you selected in error.
You can either load up a folder (or all albums for an artist) at a time or you can simply drag a track from iTunes into Yate which will load all tracks in the same album. (only the dragged files will be pre-linked).
I suggest you operate in this manner and build up an action which performs the basic editing steps that you want to perform over all your tracks. I've been refining my 'goto' action for about six months now and I'm sure I'll continue to tweak it in the future. Just for your information I have a series of nested actions which edit my tracks saving the changes to iTunes, unless it's a new album in which case the tracks are also added to iTunes, moved to a NAS drive and added to my Album Database. Doing this over a smaller set of files allows you to better see the changes and to revert if you're not happy.
Once you have your actions defined, you can run it and all your tracks through the Batch Processor Wizard and edit them all on a single run.
Hopefully your freeze has ended by this point. 🙂 If not, let me know and we'll discuss more detailed troubleshooting.