Sorry about the Wall of text.
I've been using Lightroom for since version 1, but am having big problems using the Library module lately. Import is as fast as before, but using the Library or Loupe to view images is borderline unusable. When going from Loupe to Library or vice versa Lightroom freezes for 10-20 seconds.
Scrolling through Library works fine, but when selecting an image there Lightroom freezes again, for the same amount of time. The same thing happens when viewing one picture at a a time ("Fit", not 1:1), "Loading" and frozen Lightroom for too long.
It has gotten so bad that I have to use a third party option to "cull" the images before import, instead of doing it in Lightroom, since the delays were both annoying and unproductive.
Lightroom also takes long to open up than previously, while there is no huge increase in the size of the catalog (150k pics). Startup takes up 30 seconds now, and it looks like the program is "struggling", displaying the left hand pane with the folders etc with a low "fps".
I have increased the cache to 60gb, on a separate SSD drive, while Lightroom and catalog are also on SSD-drives.
I moved created a new empty preview folder, and nothing changes. Same when renaming the folder the images are in, so only having the smart preview - no change.
Creating a "tiny" (1000 images) catalog makes no difference; exactly the same experience.
I feel that I have tried tips that I have seen here, but I am not getting anywhere. I am using a i7-5820k on an AsRock X99 Extreme motherboard, with 32gb DDR4-2133 memory, which I believe should be able to handle Lightroom. Not experiencing any problems with any other applications. For instance with having open multiple 500mb+ tiffs in Photoshop.
Any advice on what to try next?