could you provide the error you're seeing, if you get a 500 that's unrelated to ClojureScript compilation as it means there's a problem serving the request server side
cljs runtime itself is around 100kb, then baking-soda reactstrap wrapper adds another 100kb, and cljs-ajax adds another 100kb or so, if you just use cljs runtime + reagent it'll end up at around 350kb
so it's roughly normal from my experience