Random IO

Random read/write performance matters if you copy a lot of small files or use the drive as storage for games/applications that are directly started off the drive.

Sequential IO

Sequential performance is relevant when you copy large files—videos, for example.

Sustained Write Speeds

Sequential write speeds start out at up to 500 MB/s and remain at that level until 300 GB have been written, which is a lot. Once the pSLC cache is exhausted, the controller has to write to TLC directly at lower speed. Rates go up and down again intermittently as the pseudo SLC cache is flushed to TLC in the background. Just like with all pSLC mechanisms, rates recover fairly quickly when writes stop and the SLC cache gets flushed to TLC.