From Microsoft: About Bootvis.exe
Bootvis.exe is a performance tracing and visualization tool that Microsoft designed to help PC system designers and software developers identify performance issues for boot/resume timing while developing new PC products or supporting software.

Please note that Bootvis.exe is not a tool that will improve boot/resume performance for end users. Contrary to some published reports, Bootvis.exe cannot reduce or alter a system's boot or resume performance. The boot optimization routines invoked by Bootvis.exe are built into Windows XP. These routines run automatically at pre-determined times as part of the normal operation of the operating system.