SnappyMail

Simple, modern, lightweight & fast web-based email client.

Mobile booting with ~144 KB download (using Brotli) and up to 99% performance grade by Lighthouse.

This is a fork of the much appreciated RainLoop, but with massive changes to be compatible with (mobile) browsers in 2020.

Checkout the source, releases and wiki at GitHub

Here's a short comparison

Demo's

SnappyMail and RainLoop

Lighthouse

Here's the mobile performance comparison of the two demo's on this server (with Apache deflate off).
Here's the mobile performance comparison of a large mailbox on a different server (with Apache deflate on).
Taken with a 200Mb/s connection on a moderate Intel I5 PC.
You may do your own tests in the Chrome/Chromium developer tools.