You may notice an issue where the Windows Update (WUAUSERV) service will be spiking one of the logical CPUs on servers running Exchange 2007 with automatic anti-spam updates turned on. This will include any SBS 2008 installation where Forefront for Exchange was installed as part of the setup. Please note that the service displayed will by SVCHOST, since WUASERV runs inside SVCHOST.EXE.
The issue is resolved on Windows Update backend, and should clear automatically on next WSUS server’s sync. Here’s to start a manual WSUS sync: Open the Windows SBS Console; Click the Security tab; Click the Updates sub-tab; Click the Synchronize now task; Click Ok to start synchronization; Restart the Windows Update service once synchronization finishes (optional)
Source:→ SBS blog