Microsoft or other places suggest to turn off Superfetch if you use SSD, like this one:

But with Superfetch and Prefetch:

  1. There isn't any access write to SSD involve, while access read for SSD suppose to be unlimited.
  2. RAM is faster than SSD.

Then, why should we turn off Superfetch?


If prefetching is enabled, Windows collects statistics about applications in %WinDir%\Prefetch. This statistics change very frequently, which causes a lot of writes to the SSD.

See this FAQ article.

  • @aughingthunder This answer is why it's always been recommended, by both Microsoft and OEMs, to disable prefetch when installing to a SSD, as flash has a finite life span and therefore the user loses more than they gain by having it enabled for the negligble, if any, improvement. A middle range SSD will perform ~100K IOPS, whereas a mechanical HDD can only do ~10 IOPS [Input/output Operations Per Second].
    – JW0914
    Dec 30 '19 at 6:05

Yes, because the speed differential between RAM and a physical spinning disk hard drive is much larger than between RAM an a SSD. Also the access time of a hard drive is >10ms is most cases and less than 1ms for an SSD.

When data can be fetched from the SSD at 500-550mb/s the amount of time you save is negligible. Plus you can have that RAM free to do other important tasks. Also the cpu and memory overhead for managing the cache are no longer justified at those speeds.

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