P: Large catalogs: Filter folders + import = huge slowdown or freeze

Summary

If you have a large catalog and use Filter folders, then next time you use Import (or Synchronize or Drag&Drop, ...) it will take a lot more time than usual or essentially freeze Lightroom. Catalogs with 10.000s of photos -> LR freezing for seconds or tens of seconds. Catalogs with 100.000s of photos -> LR freezing for minutes or hours.


Windows 10, Intel i7 6700K. No plugins were active, not even the standard ones like Flickr or Adobe Stock. I have made a lot of tests and this is what happens:


Step by step reproduction

1) Open LR
2) Just for comparison: Import 10 or more files files - this takes seconds
3) Remove those files from the catalog
4) Use Filter folders in the left panel: Write "aaa" there, Enter, then clear the text by clicking on the cross. Filter folders should therefore be no longer be active
5) Import those same files again - if you have large catalog, this now takes much more with LR possibly freezing after about 6-8 photos imported.

How much time it takes depends on the size of the catalog:

• With an empty catalog, there is no slowdown.
• With a small test catalog containing around 20 000 photos it took around 10 seconds instead of the original 2 seconds without using the Filter folder (LR became unresponsive during the process, that didn't happen without Filter folder)
• With my main catalog containing 270 000 photos, the import of 10 new photos causes LR to completely freeze for 63 minutes. (But of course, normally I just kill it after a minute and avoid Filter folders like plague.)

Same freeze happens when using the filtering by color labels.

It is sad as it would be a useful feature 😞