There are times when I’ve built up a page with complex Data View Web Parts (DVWPs) which take a *really* long time to load in SharePoint Designer 2007. The usual reason for this is that I’m using a Web Service as a DataSource which returns a large amount of data or that I’ve got many DataSources in an AggregateDataSource.
In the former case, setting the Show with sample data option usually doesn’t help, as you don’t always have the option to limit the returned data. This option can be a real timesaver in many cases, however.
In the latter case, it’s simply that SharePoint Designer has a *much* slower rendering engine than your browser does (at least that’s what I think it is).
There’s a trick for this when you need to make quick edits. You can right click on the file name and choose Open With > SharePoint Designer (Open as Text). Depending on what other programs you have installed on your machine and how you have things configured, you may see other options as well, like Notepad or Visual Studio.
By opening the .aspx page as text, SharePoint Designer doesn’t try to do any interpretation of the page whatsoever. This means that you can almost immediately make your edits, but you get none of the usual Intellisense, syntax help, unescaping, or color coding. So it’s great for quick edits or making changes where you really know what you are doing, but it’s hardly where you want to spend all of your time.
By the way, the exact same technique works in SharePoint Designer 2010, though I haven’t needed to use it much yet. I don’t know if I’ll run into the same slow page stuff there or not. One would hope that the rendering engine there is better, though since Microsoft doesn’t look at SharePoint Designer as a real IDE, they may not have made that sort of improvement. I’ll let you know what I find as I do more SharePoint 2010 work!