I don’t know that I agree with the statement: “ReadyBoost focus is reducing RAM usage, instead of increasing hard drive access times.”
It is primarily used for caching files, so they do not have to be read from the hard disk again, which is slower. Unless you have an SSD drive, I believe you would probably notice the difference. I saw a big difference, especially with things associated with the Interface.
On Windows Vista, less-than-mature algorithms did lead to reduced performance with ReadyBoost enabled on a system with large amounts of memory. These algorithms were improved with Windows 7 such that even a system with large amounts of RAM would benefit from ReadyBoost, and repeatable performance gains have been reported. See this blog post for more details.
With commonly accessed data, ReadyBoost uses the flash memory cache for small random reads in tandem with the hard drive for large sequential reads, taking advantage of the fast random I/O characteristics of flash memory. However, flash memory is usually slower for sequential I/O than hard drives. It appears that algorithms related to this process were poorly tuned with Windows Vista, but this been resolved with Windows 7.
ReadyBoost is NOT a cache.
It is a mirror for your swap file. The most used virtual memory pages go there, and to HDD both.
That is the reason, why there is no reason using it in systems where both SSD and HDD present – IT IS NOT A CACHE.
The problem is that WIndows decides where to read from basing on disk load. But during heavy and average CPU load it still prefers USB. Attempting avoid HDD interface bottleneck, it hits the system I/O bottleneck. It still has to do a lot of work with NAND flash, and then buffer and decrypt the data, before fetching it to physical RAM.
So, it often happens, that ReadyBoost not boosting, but freezing the Windows down.
I have done some tests. I5 8gb Ram 750 hdd.
IF you have HDD, putting a pendrive ready boost on a usb 3.0 will improve boot time by 40%. Dont know about other program performance.