Some MS Windows installations run slowly for several minutes, particularly after start-up or resumption from power savings mode. After several minutes, CPU usage will drop and the system will run normally. This may be caused by local caching of DNS lookups, which can be disabled. There will typically be no detrimental effects.
In task manager, look for 100% CPU usage by svchost.exe. The user name is NETWORK SERVICE.
Start Button --> Run --> services.msc
Right-click on "DNS Client", and choose "Properties".
Change "Startup Type" to "Disabled".
Either restart the system, or press "Stop" button.