Other things that have gotten slower by design
Another feature of Visual Web Developer which is certain to seem slower than VS 2002 or 2003 is the opening of "miscellaneous files." These are files which (should) sport Intellisense but are not part of a web or a project. In earlier versions of VS these simply didn't have Intellisense hooked up. So, for example, if you typed "Response.", nothing would happen.
VWD 2005 creates a hidden, "miscellaneous" project to wrap around the miscellaneous file. It searches upward, looking for an actual web the file may be a part of, looking for a /Code folder, web.config file, or other clues (I can dig these up and enumerate them if anyone's vitally interested) and figures out where to "root" the web. If a web is discovered and it's not from a previous version of VS, the project system does what it would for a normal web; /Code Intellisense is generated, global.asax is honored, everything.
If you open two miscellaneous files, you may get one or two miscellaneous projects. If you opened c:\foo\defalut.aspx and c:\foo\info.aspx they'd both share the same hidden project. If you opened c:\foo\aspx and c:\bar\data.aspx there'd be two different miscellaneous projects. Most of the spin-up is asynchronous but the memory footprint of the Intellisense and type resolution services is noticeable.
Has anyone out there run into problems with this? Is double-clicking on a file on the desktop to make a tweak too slow? Do you get unexpected Intellisense (or none at all) with these types of files sometimes? Does the Intellisense make you happy to leave notepad behind at last for this type of operation, or does the startup time make you right-click and "Open With..."?