TL;DR:UsefulPS:SSD user just ignore SuperFetch, as it has been disable by default, it don't affect much for you, except you like to put some software on HDD.Some user said that, he disable SuperFetch and getting a slow boot of OS, just leave it as default.

On weibo, Kai-Fu Lee said:Windows Vista/7 的SuperFetch服务是为企业应用与大型协作软件而设计的, 个人用户没有必要开启. 在大型企业中使用的专业软件中与企业策略管理, 数据库启动过程中会长达10分钟之久. 而运用SuperFetch, 可将启动时间降低到6分钟以内. 而对个人的用户来说, 平时使用的日常软件本身的启动时间非常短 通常在1-2秒之内, SuperFetch这时候的提速只是0.2~0.5秒, 基本可以被认为是毫无作用, 而且还会加大对硬盘的监测(损失CPU性能时间)与读取时间(增加硬盘IO寻址线程分配). 而SuperFetch对游戏程序是无效的, 对于个人用户与游戏玩家来说, 开启此服务只会无形损失CPU的性能时间与损失硬盘IO寻址的线程性能.
The SuperFetch service on Windows Vista/7 is design for Enterprise Applications and Large-scale collaborative software, that are no need for Individual users. As the Professional software and Enterprise Policy Management that using in Large Enterprises, the time for database to boot will be 10+ minutes.
By using SuperFetch, it will reduce the launch time to 6 minutes or less. For Individual users, their launch time for daily software is very short, normally it just need 1-2 seconds. At this time, SuperFetch will only speed up the launch by 0.2~0.5 seconds, which can be considered as useless, and it will increase the monitoring of the hard disk(lost of CPU performance time) and load time(increase of hard disk I/O addressing thread allocation).
So SuperFetch is useless for game program, for Individual users and gamers, running SuperFetch will only lost the CPU performance time and the performance of threads for Disk IO addressing.
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This is what I think, SuperFetch only affect cool launch of software(reduce the time to launch), and it decrease the OS boot time to 20-30 second.
And most of the software, it only slow on cool launch, but not the warm launch.
If we don't shut down or restart the computer, we will only warm boot for every software that we boot before.
And this
Whenever memory becomes free-for example, when an application exits or releases memory-SuperFetch asks the Memory Manager to fetch data and code that was recently evicted. This is done at a rate of a few pages per second with Very Low priority I/Os so that the preloading does not impact the user or other active applications. Therefore, if you leave your computer to go to lunch and a memory-intensive background task causes the code and data from your active applications to be evicted from memory while you're gone, SuperFetch can often bring all or most of it back into memory before you return. SuperFetch also includes specific scenario support for hibernation, standby, Fast User Switching (FUS), and application launch. When the system hibernates, for example, SuperFetch stores data and code in the hibernation file that it expects (based on previous hibernations) will be accessed during the subsequent resume. In contrast, when you resume Windows XP, previously cached data must be reread from the disk when it is referenced.
http://technet.microsoft.com/en-us/magazine/2007.03.vistakernel.aspxhttp://www.osnews.com/story/21471We also compared the startup performance of a couple of applications, including Outlook 2010 Beta, which needed five seconds longer to start and navigating between folders felt sluggish. Launching even the very slim Google Chrome browser took about seven seconds, whereas the original test only took four seconds. This is not good.
http://blog.tune-up.com/myth-buster/myth-busted-why-disabling-superfetch-on-vista-and-windows-7-is-a-bad-idea/
http://www.portablesoft.org/one-click-optimization-rumor/So, I already know the answer.

And we know that some person speak without testing and proving it.

Another PS:The system will slowing down after 1 minute OS has been completely booted, as It(SuperFetch) will start writing data and reading old data about the 9 OS boot it has been recorded before, optimize it.

But, windows 8 user that using Fast Boot don't facing this issue, as I know, SuperFetch don't optimize for Fast Boot yet.
Edit:Changed the Topic/Subject for showing the meaning correctly.