You'll notice all these review sites keep their tests nice and short. That way Samsung stays happy and keeps buying ad space. If they tested a drive months apart Samsung would be exposed with those floppy disk slow reads.
None of these tests give the consumer any indication of the degredation of the performance of the SSD over time. While my systems have been become more powerful and the software has been updated, the performance of my main SSD used mostly for for W7 and hardware drivers and as measured by Passmark runs has declined by 38% in about three years.
@Gurg, as SSD over time, either via temperature or usage or amount of data filled performance declines. if you secure erase and install new window and it'll back to brand new performance again, tbh i think this article cover most of it, maybe you're just confused between a good ssd or uncleaned window files slowing down your system.