One non-cynical take on why modern software is slow, and not containing optimizations such as these: The standardization/optimization hypothesis.<p>If something is/has become a standard, then optimization takes over. You want to be fastest and meet all of the standard's tests. Doom is similarly now a standard game to port to any new CPU, toaster, whatever. Similarly email protocol, or a browser standard (WebRTC, Quic, etc).<p>The reason your latest web app/ electron app is not fast is that it is exploratory. It's updated everyday to meet new user needs, and fast-enough-to-not-get-in-the-way is all that's needed performance wise. Hence we see very fast IRC apps, but slack and teams will always be slow.