Turns out this was an issue with deduplication - it was using a deduplication run atop linked list instead of a dedicated auto-deduplicating data structure such as hash set or tree set.
I've switched the data structure for files to import to TreeSet; it should fix the issue. I'm still testing whether it fixed it because importing 35,000 tracks in the old implementation is indeed slow!
Thanks for reporting the bug!
Turns out this was an issue with deduplication - it was using a deduplication run atop linked list instead of a dedicated auto-deduplicating data structure such as hash set or tree set.
I've switched the data structure for files to import to TreeSet; it should fix the issue. I'm still testing whether it fixed it because importing 35,000 tracks in the old implementation is indeed slow!