You can use Msconfig in Windows to trim down startup programs and services.
First use Msconfig to take some programs out of the startup list
Then go to the Services tab of Msconfig and check the "hide all Microsoft Services" box
Now you will see all the services installed by 3rd party software, you can Google each one and make your own determination if you should disable it, disabling all Non Microsoft services is ok, but some programs may depend on them to start and run, if you do not use these related softwares then disable that associated service.
Reboot the PC
There will be little difference between processes for a regular account or a Guest account, most are hidden when in the guest account for security reasons, but they are still running.