svchost.exe doubling in size after full scan

Hi, I have several instances of svchost.exe running, one of which uses notably more memory than the others. I'm aware that this is normal, however, a problem arises whenever I run a full scan with Norton. The larger one will more than double in size, going from around 110,000k to 260,000k plus. The process retains the memory even after the scan finishes, returning to normal only after I reboot the computer. So my question is whether or not this is normal behavior, and why it holds on to the memory even after the scan is done.

For reference, the services attached to this particular svchost are: Uxsms, Trkwks, SysMain, PcaSvc, Netman, hidserv, CscService, and AudioEndpoint. No other services appear during or after the scan.

Thanks