SSDs slow down as they get filled with data, so I was wondering if there any percentage of the drive I should leave unused to keep my drive working at full speed?
I have an 850 EVO 250GB.
First off, thanks for the question!
SSDs come from the vendor with a certain level of overprovisioning (OP) baked in. Most drives are set somewhere around 7% capacity, this means your 240GB drive is 256GB and so on. Samsung Magician recommends users set OP to 10% for heavy workloads, but for typical gaming, the default settings work fine.
If your performance issue arises after filling the drive past 75% capacity, I would honestly look towards migrating to a higher capacity solution. No level of overprovisioning will help an SSD that's full of data.