Svchost.exe is a generic host process name for services that are run from dynamic-link libraries (DLLs). There can be multiple instances of Svchost.exe running at the same time. Each Svchost.exe session can contain a grouping of services, so that separate services can be run depending on how and where Svchost.exe is started.

Looking at your log I see at least a couple things which "could" be causing this "svchost process hogging the memory" one of them being Auto Updates.

Now a good tool to use to narrow this down is Process Explorer v11.04
You can at least determine which processes are being controlled by looking at the PID number of the svchost in question. For instance, on mine the svchost.exe PID with the highest memory usage is 1072. By using the Process Explorer I know that 18 different services are controlled by the svchost.exe 1072, they are listed by name if you highlight that one and then click Properties.

You have numerous, unnecessary auto starting programs and services showing in the log. All of these then will run in the background all the time, some would be contained within the hogging svchost process, some would not but all will be using some available memory. Most likely culprit would be the auto updates...Windows, SunJava, Google to name a few, but the Windows auto updater for sure. Myself, the only program I have set to auto update is my anti virus program, all others I have auto update turned off and I do them manually.
Here is a list of those auto starts from your log which are unnecessary and can all be run manually;
SigmatelSysTrayApp
Dell QuickSet
CTSVolFE.exe
ISUSPM Startup
ISUSScheduler
SunJavaUpdateSched
QuickTime Task
TkBellExe
Adobe Reader Speed Launcher
MSMSGS
Digital Line Detect

DSBrokerService
Google Updater Service
iPod Service