what program you recently installed or upgraded? svchost.exe related to system process or backend program. or you can try to STOP those service you don't need.
go to Control Panel >> Administrative Tools >> Services and STOP all process EXCEPT the following
COM+Event Syetem COM+System Application Cryptographic Services DCOM Server Process Laucher Distributed Link Tracking Client Distributed Transaction Coordinator IPSEC Services Logical Disk Manager Network Connections Network Location Awareness Plug and Play Protected Storage Remote Access Connection Manager Remote Procedure Call Security Center Server Shell Hardware Detection SSDP Discover Service System Restore Service Terminal Services Workstation
Try to STOP Other services and watch whether your CPU still 100% or not.