How to disable MyEclipse visual HTML designer

My computer lags for several seconds when I open an HTML file in MyEclipse, or make a major change to a file that's already open. I suspect that the WYSIWYG part of the visual HTML designer is responsible; is there a way to turn that off but retain the color-coded text editor/formatter? I also don't care about the "preview" feature, if that makes a difference.

I have faced the same issue. Go to Window > Preferences > General > Editors > File Associations and pick the file extension for which you would like to disable/enable the designer. Hope that works for you.