I use SSDs for boot, operating systems, and all stupid deletable temp/swap/page/etc stuffs. My experience is that empty drives run faster than filled drives, regardless what kind of file system or fragmentation or actual data might be present. Experts often disagree or argue that capacity-vs-performance impact should be insignificant, but why not keep things as lean and clean and fast as possible?
I keep games and movies and all but the most essential apps on ye olde HDDs and just load things through ROG RAMDisk whenever fastest performance is a concern.
The smallest-capacity (128GB) Samsung 850 Pro SSDs has less integrated DRAM cache than its larger-capacity siblings. As usual, this bottlenecks all Write throughputs whenever the flash controller sustains peak Write activity (Sequential and Random). Not as limiting on these SSD models as on many other models, however.
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