I think that an approach like that would have severe performance implications. The really impressive thing about Textmate is how fast it is in relation to Eclipse and Netbeans.
I think the issue with Eclipse is the latency in whatever Java uses currently for drawing widgets (SWT?).
Right click a project in Eclipse on your Core 2 Duo, and time how long it waits for the context menu to show up. Then right click any other IDE, text editor, or non-Java app, and attempt to do the same.