PCIe v4 NVME drive - why so slow?

[Quartz]

Sabrent are launching a 4 TB PCIe v4 NVME drive. The read speed is 40% better than v3 but the write speed is only marginally better:



Why is this? Why aren't both - particularly read, near double?

 

[Quartz]

That depends upon the size of the cache and the speed with which the cache controller can write to the rest. For instance Linus Tech Tips looked at an 8 TB NVME drive and saw no drop in performance long after the cache should have been filled.