A prominent question I’m always asked when something goes wrong with Vista is; Why are there so many instances of “svchost.exe” running, is that why it’s so slow? While the answer most likely is yes, it’s important to understand what svchost.exe is and how it work with Vista.
Without getting too technical, the How-To Geek has the best explanation for what svchost.exe is: “some time ago, Microsoft started moving all of the functionality from internal Windows services into .dll files instead of .exe files. From a programming perspective this makes more sense for re-usability, but the problem is that you can’t launch a .dll file directly from Windows, it has to be loaded up from a running executable (.exe). Thus the svchost.exe process was born.” In other words, many of the programs you use in Windows require a separate instance of svchost.exe to function properly, that’s why there are usually so many instances running simultaneously.
While more instances mean more load on your CPU, most of them are required for vital Windows components. The easiest way to reduce the load is to find out which svchost.exe process is associated with programs you don’t need. That way, you can eliminate several programs and processes while keeping the required ones in tact. So, how do you figure out what programs are associated with each instance of svchost.exe? It can all be done using the Windows Task Manager.
Open up your Task Manager and select the “processes” tab. Scroll down to find the grouping of svchost.exe and do the following for each instance; Right-click on the instance and click “go to service(s).” This should switch you to the “services” tab and highlight the associated service. Go down the list of instances and notice any services that you can do without. Many times services people have really never used are constantly running in the background taking up valuable CPU power. Write down all the services you feel comfortable disabling, close the Task Manager, and open “services” under “administration tools” in the control panel.
You can now find the services you wish to cancel, highlight it, and press the “stop” button at the top of the window to disable it. Before you stop it, you should also disable it from opening during startup or you’ll be back to square one. Before stopping it, double-click the service and click “properties.” Change “startup type” to disable and click OK. Now stop the service, and it should never start again at startup. Continue this process for each instance of svchost.exe and you should notice a difference. Look for the CPU usage next to each instance and try to eliminate the ones using the most juice. Hopefully this will help speed up your system a tad, or at least get you on the right track.