With the possible exception you mentioned (I switched to FastMail long ago to get back to that snappy feeling) my experience with SPAs is that they all add 10 m

With the possible exception you mentioned (I switched to FastMail long ago to get back to that snappy feeling) my experience with SPAs is that they all add 10 megs of JavaScript up front and several dozen kbs of JSON or similar per click to save a couple tens of bytes per page of HTML. I pulled those numbers out of the air obviously, but I'm not sure that they're even exaggerations…