Hi since your computer is running very slow i would update your anti-virus definitions to the latest signature and then run a thorough virus scan as one of the reasons a computer can run slow is thru being infected.
svchost.exe can run any .dll process. We'll have to find out which are the processes running under that svchost.exe.
Get Process Explorer and look for this particular svchost.exe - best by looking into the CPU column. Then either hover over that one or even better look into the properties of that svchost.exe. Under the services tab you should see something like the picture (could be less or more processes). Open the little window such that all processes are visible and make a snip picture like mine. Post that here and we'll have a look.