I've been having the same issue for many months. From what I managed to diagnose this: In the library module, if we press any keyboard shortcut, e.g. "B" to add a photo to the quick collection or to flag a photo, Lightroom freezes for a few seconds, 5-30, depending on the computer configuration. On the other hand, when We clicked the mouse to add to the quick collection, Lightroom did not freeze. The issue is not related to the hardware configuration or the Antivirus program. So, I looked into what Lightroom is doing with our hardware resources. Lightroom reads a lot of data when it's freeze. Not write, only read data. The C: drive is always the one under load, even if the Lightroom catalog is on a different drive or the cache is on a different drive. The C: drive is always under load. Even if Lightroom is frozen, when we still press the "B" buton, Lightroom still reading data from the disk reaches 300 MB/s! While Lightroom freeze it runs Photoshop in the background, and if you have multiple versions, it can run several versions at once. Then Photoshop reads many paths to RAW files from the Lightroom catalog, a lot of paths to RAW files are read, even those not related to the currently added file to the quick collection. Why it does this I have no idea, but it definitely causes Lightroom to freeze. The problem sometimes occurs after updating Lightroom, and 100% occurs after updating the Lightroom catalog to a new version. I suspect Lightroom is looking for same information in the RAW catalogs, as if some information was lost when updating the Lightroom catalog to a new version. These are just my guesses. I hope Adobe will fix this problem. The problem is clearly noticeable when the Lightroom catalog is very large, e.g. 100,000 files. The solution is unfortunately random and sometimes it works, sometimes it doesn't. 1. Sometimes restarting the computer helps. 2. If that doesn't help, you must create a completely new Lightroom catalog from zero. Then import all the data from the old Lightroom catalog into the new one. This process takes a very long time. I hope I helped someone and showed Adobe where to look for a solution. ... View more