Possible causes of your problem based on the tiny amount of info you have provided:
- Malware or other junk loading at startup. - Failing hard drive. - Problems with your router or internet connection.
Is the problem that your computer is slow in general, or does it boot quickly but takes a long time to pull up a web page? You need to provide more details about your computer, your internet service and the nature of the problem.
Behind every good computer... is a jumble of wires 'n stuff.