Does this webapp really need to be 20 MB? What all is being loaded that could be deferred until it is needed, or included in an “optional” add-on bundle? Is there a possibility of a “lite” version, for bandwidth-constrained users?
While Antarctica is an edge case, this article illustrates some of the motivations behind my text-first website.
By trimming the excess not only do you get to the core of the app or website, but it also loads faster.