I'm not sure about a tool that reports which programs are causing e.g., your laptop to be slow. That's usually what you should investigate yourself. There are of course, many benchmarking programs, and with the SysInternal Tools from Microsoft, you should be able to do almost all the investigating you need to do (manually), if you want to follow this approach.

Often just by opening the task manager, you'll be able to see what takes up all the memory of your running processes, including CPU time. I can hardly believe any group policy will slow down any computer, except if this policy runs a lot of programs for fun.

Some Anti-Virus applications are known performance killers, especially when you browse a website, they may lock completely up until a website has been evaluated as safe or not safe.

Sometimes, it is just the programs you're using that are slow. (As in they could've been coded better, but you'll have to live with that.)

I won't deny that there isn't such a tool that you're looking for, out there on the vast Internet, but often if you take the manual approach, you'll get a lot further in making your computer faster, by e.g., disabling all services you don't need. (I've done that, because there's no need to run the print spooler service when I don't have a printer.)  I know it only takes up ~1mb ram, but on this point I don't want to waste it, if this 1mb can make some of my pentest tools faster on my Windows installation. (Of course I run Linux as well, which is often faster than Windows except at flash playback xD.)