I have had problems with freezing Lr 5 from the first version of Lr5. That still happens, especially after several use of Spot Tool.
One day I observed, Lr is not trying to use more than half of the RAM (in other words, Lr was ignoring second bank of the two existing RAM), what was strange to me, because Ps CC and Lr 3.6 & Lr 4.x used RAM without any problem that time.
I checked the RAMs and decided to swap banks each other. After that Lr starts to use whole RAM and work, especially after installing 5.4. But the same, after use several Spot Tool instances (from 5.4 a little more than before), especially not that point but irregular spots and spots covered other spots, Lr freezes as usual.
Lr 5.6 applies whole job doing before to the files a little quicker (e.g. while opening the catalog or photo in Develop Module), but any move in the history on the file with Spot Tool gives the same dramatic waiting time to see result (30 sek is average) and I observe artefacts (black boxes) during apply in that place, where bars overlays calculating photo. What I think is the problem of the app with graphic card and with this Spot Removal Tool. I did not the same with old version of Lr, but I have the same card and other hardware. So, find the guilty
So, what I think, Lr 5.x is really strange app hardware sensitive and has bad behaviour, performance issue included.
