Hi
Probably the worst thing I have ever done when I installed Norton. It has slowed my computer down so much - it takes ages to load and blocks emails that I have been having for years. Has anyone ever spoken to anyone at Norton? All they do is make you attempt to find a solution by searching all their suggestions but none of them answer my questions. (Spent far to much time searching). I shall be uninstalling it and go back to McAfee
When you installed Norton, was there another security program on your system? If so, did you fully remove it using the removal tool for that program before installing Norton?
What are your system specs, and Windows version?
i have never experienced a bad or constant slow down with norton installed
only thing close would be after a new build / patch it may lag ( depending on size of update) for minute or two but other than that i see no slow downs at all