The MATLAB startup accelerator is quite simple, it reads in the files that will be loaded/run when MATLAB is started then the process exits. Testing showed that this can dramatically improve the startup times of MATLAB. There is no effect on system performance other than the file io while it is running and if you had other data in system file cache it might get flushed and need to be reloaded.
Now my opinion's, not Mathwork's, on when this is is likely to be most helpful and when it may not be as helpful.
I believe you will see the biggest improvements on a machine with large quantities of memory that is not frequently used for other memory hungry applications. Running a memory or disk intensive program between the time MATLAB starter has run and when you start MATLAB may nullify any improvements.
I expect little benefit or harm from the accelerator if MATLAB is installed on a local SSD.
Windows 7 superfetch dynamically performs a similar operation if you frequently use MATLAB then superfetch may be doing the same thing for you already.
In the case of multiple installed MATLAB versions I suggest disabling the accelerator on all but the version you use most often unless you have >8GB memory and frequently use multiple versions.
In conclusion this is a trade-off that may or may not be to your liking or helpful in any specific usage scenario: MATLAB Startup time is reduced at the expense of system overhead when the scheduled process runs and possibly when it runs again at user login.
