Svchost is an executable file that runs in the background of the Windows operating systems. SVC is a generic name for a process, or program that runs from dynamic link libraries or DLL files. As the name is a generic name given to a large number of process that run from .dll files then it is possible to have a lot of them running in the task manager. SVC host processes are required so that the .dll files run correctly and allow the computer to continue functioning.
If you are noticing there are a lot of Svchost.exe programs running in your task manager there are a couple of different reasons that there will be multiple svchost processes running. An explanation of the reason there maybe multiple SVChost processes running are below.
The first reason there might be multiple SVChost processes running is because there are multiple programs requiring direct links to the needed dll files. If this is the case there is not much that can be done other than examining which programs are running and possibly shutting done the programs that are not required to be open at that particular time.
The second reason that there might be more than one SVChost running is not as good. This is because there are multiple viral and malware infections that run under the disguise of SVChost as many times it is not recommended to shut down this process many people are reluctant to do so; thus allowing the bad program to continue to run. If your computer has gotten a lot slower and is moving as fast as a slug there are very easy ways to find out if you have an infection such as the LSASS infection that is causing this slow down. The first thing to do is to ensure that the anti-virus program you are using is up to date with the list of known files that are bad, or the definitions within the program. The second thing to do is to run a full system scan and see if there are any infections within the system. If there are no infections identified the next thing to do is to do a full system update and ensure there are no open vulnerabilities within your operating system.
The final thing that can be done to speed up the system from the Svchost effects is to run a registry cleaner. As Svchost runs in tandem with many dll files a registry cleaner will identify and remove duplicate dll files, or corrupt files from the registry. With a cleaner registry the SVChost processes will not need to look as hard or as deeply through the registry. With this easier access the SVChost programs will not take up as much of your systems performance.