After today's 10.1 update, browsing photos in the Library module is a nightmare. When Lightroom is launched, your photos are browsed at normal speed. After reviewing several hundred photos, it starts to slow down (at the same time the CPU usage increases to 60-80%). It takes about one second to advance to the next photo. After Lightroom restart, everything returns to normal.
CPU has enough power, memory is 50% full. The LR directory is on the NVMe drive. I am using Smart Previews. Turning GPU assistance on / off has no effect.