Swift Performance Lite has limited features, and we are not planning to add new features to Lite version. Of course bug fixes, and compatibility updates will be released, but new features will be available only in Premium version.
We also provide Premium support for Premium version, which means we are happy to help to configure the plugin, find any speed issues, even add new features to solve your exact speed issues. For Lite version we provide only Basic support (to keep it compatible and fix major 3rd party conflicts).
As for the main differences in the features, with Premium version you have: unlimited image optimizer, extended WooCommerce features, server push for HTTP2, remote cronjobs, critical icon fonts, compute API (for lower CPU usage), whitelabel, etc.
You can check differences more in details here: https://swiftperformance.io/why-should-upgrade-pro.