Do you mean after the OS loads and you reach the desktop screen it a long time before you can click and use anything?
If so then you should investigate your Startup programs. Click "Start", "Run" and type in msconfig, then press enter. Go to the "startup" tab and untick any unnecessary programs or post a screenshot here so members can help you decide which if any are not needed to start with the computer bootup.
It may be a good idea to clean out your temporary files and perhaps post the computer specs in case it is hardware related, ie low on RAM.