Since Norton comes as a security center packaged with various features for device protection (antivirus, spyware, and network intrusion detection tools), it may slow down your computer. However, by itself upon installation, Norton antivirus does not slow down the system processes. When Norton antivirus starts the scan of your computer looking for any malicious files, your computer may slow down. This is only due to the scan and since antiviruses can consume a lot of RAM. Once the scan is done, your browser speed and speed of all the programs and apps will return to normal. In order to limit the whole slow-down process during the scan, you should make sure your device is compatible with the Norton Security package you want to purchase.