Under the Boot Activity Graph, it shows "Prefetching" (Init Time: 19.91 sec). So does that mean I should disable prefetch??
No disabling Prefetching will cause the overall time of Windows to Boot to increase significantly. If you look again you will see that the prefetching is happening simultaneously during the driver load portion. Prefetching is what accelerates Windows XP boot time. DO NOT DISABLE IT!
By default Windows optimizes the boot files automatically every 3 days at system idle time (10 minutes of inactivity). Bootvis simply invokes this to happen now, instead of waiting three days. Anytime something with your boot changes, new drivers, new applications that load at startup ect... you would have to wait 3 days for your boot times to get optimized. Or you can simply run Bootvis and have it happen now. This is why it works and this is also why Microsoft says it does not do anything that Windows does not do automatically, both are true, it simply comes down to how soon you want your boot performance optimized.