Occassionally Visual Studio 2005 takes a while to switch tabs from a C# file to an html file.  Even the act of opening aspx pages started to become slow.  It seemed very odd to me that this text file should take more than a second to open.  After a quick google search I had found the solution; disabling the navigation drop-down and validation errors in the html editor.  In fact I disabled the navigation bar on all languages except for C#.

Another tip is to uncheck the Auto ID elements on paste as well as the Auto insert close tags.  These are two things that annoy me when they are checked.  I do not want my server controls getting a "Textbox2" ID.  It is more efficient for this to be handled by me when I decide to name the textbox rather than having to delete and replace the existing ID.  Also, sometimes I do not need to provide an ID for a server control whenever it is not going to be referenced, so an ID is not always necessary.  The other annoyance for me is the automatic inserting of the closing tags.  I am a programmer who does not like seeing <asp:textbox ...></asp:textbox>  I would rather it say <asp:textbox ... />.  I believe that whenever the closing tags are not necessary they should be avoided as it adds clutter to the code.