Tip #54: Did you know…How you can turn off intellisense for HTML/ CSS editors
If you would like turn off intellisense in HTML editors (aspx, html files) and CSS editor (css files), you could do so by going to Tools->Options dialog.
For HTML editor, go to Tools->Options->HTML->General. In the right pane, under Statement Completion, uncheck "Auto list members"
For CSS Editor, go to Tools->Options->Text Editor->CSS->General. In the right pane, under Statement Completion, uncheck “Auto list members”
Ranjini Mathrubootham
SDET, Visual Web Developer