I've updated both driver & firmwware to latest ones with no luck. Caching in windows device manager is enabled as mentioned in other threads. Temperatures during test are 70*C max (I have radiator installed). M.2 port is running at PCI-E 3.0 x4 speed. But the drive is nearly full - only 40 GB left. Is it OK to be so slow when nearly full or there is a real issue?