Which is definitely something worth measuring, as a browser pull in lots of shared libraries, which often cause some of the gap between bare window managers and desktops to decrease, especially if the WM isn't using a UI toolkit in the first place.

Also, given the memory need of modern webapps, I wonder if even the delta between the two extremes amoutns to more than one or two opened tabs. Of course, if one or two tabs is all that your machine can handle, this is significant.