Well, you have to understand a couple of things about it. And you have to be logical.
The point is that it monitors the process when you boot up the machine and then produces a report for you. You then can look at that report, see what parts are taking the most time and then do what you can to lighten the processing done there.
Some people install Boot-Vis and then run it and then feel cheated. Well, obviously you have to reboot so that it can prepare the reports before you can see the reports.
So you have to examine the menu for Boot-Vis and select the options so that when you next reboot, it will prepare the kind of report you want and then you have to examine those reports.
Some people feel cheated because they don't find any improvements to their boot times after installing Boot-Vis. Well, you have to do your part.
After installing Boot-Vis, you must set it up to prepare the reports. Then you reboot. Then you examine the reports. Then you make changes using tools like MSConfig, Services.msc, GPedit.msc, adjust the logon scripts, logoff scripts, adjust the performance setting of the System Properties Control Panel applet, perhaps adjust Indexing, adjust System Restore. There are a hundred and one other adjustments you can make depending on the report that is produced for you.
Now comes the real key. This is the important part. You must reboot your machine a second time after making the adjustments. If you don't do that, how will you ever notice a difference?
This is the most common complaint I see. People complain that they haven't seen any improvements in performance. But they never understood that they had to reboot, adjust and then reboot again to see the change.
This is not for the novice user. You have to understand some basic concepts. Perhaps this tool is not for everyone. But the problem may well be that most PC users don't understand enough about the basics to follow through the 3 or 4 steps required to make good use out of Boot-Vis.