Superfetch is now tied in with the prefetcher also, accomplishing the task of aligning data for fast boot loading, and quicker access to program parts and pieces based on the defrag alignment of your hard disk, which assists in the first run of any programs not actually pre-loaded (in ram).
Sequential reads on hard drives are many many times faster. A person could also concider this aspect of the background activity when deciding to keep it or not. Defrag routines are done out of the task scheduler and are set to occur on times like weekly at night.
If your trying to determine if you have given it enough time to "speed up your computer" give it 2-3 weeks.
Superfetch is not used for SSD drive items, because the random access time is much faster, and load time is much faster also. Alignment is far less useful for the ssd (defrag is supposed to be off for them). A speedy 7200 is a bit faster than a slower RPM drive at random, less time to the next rotation, and could be a concideration in a descision. Aligning for sequential is still many times faster.
Any quantity of writing (even endless logging) could be a concideration for a SSD drive, for a hard drive as long as it is treated well, the quantity of writing would not effect the operations. If your HD is subject to constant abuses, it might be a concideration to limit writing/reading of it, other than that it wouldn't care.
The persons patterns of running programs can be an aspect to the effectiveness of any of these alogrythms, if you have less programs you run more often, it will be more advantageous. If you have more and much larger programs and a very high diversity of operation, it will be less likely to be assisting you.
How your computer reacts to disk and cpu activity that is mostly supposed to occur without getting in your way (backgrounded), could also be a concideration. There is no doubt to the function and intention of of these alogrythms, but it could be that what You Want is "less now more later", or "more now and less later".
The quantity of ram your computer has, and the way you use it, could be a concideration, while (as always) these speeders and caches will clear when deemed to be more important uses of the ram takeoever, it is still "work" going on, and how your machine reacts, could be important to you, and completly different on another machine or how another person feels about it.
How you manually deal with the computer can also come into play, using your own versions of defragmenters (like reorder defragmentation) or any additional caches used, or ramdisks or other things where you have made adjustments to suit your own desires and patterns for how the computer operates.
"Where did you want to go today" or where did you want to have your processing, disk activity and ram use to be occuring, can be much of a users choice, and totally dependant on the use of the computer.
I have attempted to outline some of the plusses and minuses, and this is presently unfinished. There are other conciderations to how you want to use your ram, and if you use hibernation, and how many times you will be booting in a day, and endless things that can alter the total effectiveness of such routines. IT can be easily turned off without destroying anything, or causing major problems, you can give it a total chance to learn, and align, and assist, then you can still turn it off at any time without huge consequences.