The library is designed to be loaded async, so it shouldn't affect load performance. And it uses new APIs (e.g. IntersectionObserver) and techniques like throttle/debounce for all of its event tracking, so it will likely have no noticeable impact on runtime performance.

Have had major issues with reporting using this tool with an "infinite scroll" or single page app type of setup. Serious under-reporting of the history state change.

The maxScrollTracker documentation warns against using it with an infinite scroll type of page: https://github.com/googleanalytics/autotrack/blob/master/doc...

As for under reporting of history state changes, have you reported a bug? Also, how are measuring to confirm that there is under reporting?