Fix for slow NVME speeds

[nineniner]

Ive had an NVME drive issue for about a year now where the write speed (in my case) was VASTLY slower than it should, while the read speed was good. I tried reformatting, erasing, reinstalling OS, installing windows etc, and that issue persisted. It wasnt until i used the "utility" program that is usually available for an m.2 ssd form the manufacturer. I used the "clean/erase" option in there, and now its working like when new again. Dont know what it did that was special, but it worked. I had erased with disk utility, and even "cleaned" with command prompt and it wasnt working.

 

[FishCow]

I realise this necro-posting, but just thought it a good place to store other experiences and solutions to this issue.

I installed an ADATA SX8200 1TB and was getting very poor write speeds and barely acceptable read speeds.
I had cloned my installation from an APFS formatted mechanical drive, so I thought it must have had something to do with cloning.
I wiped the NVMe and reformatted as APFS and left it empty. I tested again and still the poor write speeds remained. Read speeds stayed the same also.
Out of desperation and willingness to try all things silly - I reformatted the NVMe as a FAT32 drive. Bingo - speeds jumped to what I was expecting from this tech.
After that, I (re) reformatted the NVMe as APFS and the drive continued to perform well.
I re-cloned my Mojave install from the same drive as I had previously and the NVMe performance remained awesome.

I have no freak'n clue "Wuh-Harhpend" or why this worked . . .