WD says the drive is capable of peak sequential speeds of 2,400MB/s read and 1,950MB/s write. Those numbers are marginally exceed in the straight-line CrystalDiskMark test. Bear in mind these are peak numbers that don't show the full story as the write cache is overwhelmed.
Running 4K files with a queue depth of one is tougher for these drives. Even so, the WD Blue SN550 doubles the performance of the SATA-based Crucial MX300 and gets pretty close to the Corsair Force MP600 costing 77 percent more.