Filling in Gaps
Of course, just because we don't deliver a given function to the browser does not mean that it is never needed. A key part of the overall system is ensuring transparent backfilling occurs when the partitioning algorithm mis-categorizes a function.
Does it Work?
There are many ways of measuring the load performance of a website – the time to first byte emphasizes the importance of network latency, the time to the document loaded event emphasizes the moment when users can start interacting with the page, and the speed index emphasizes visual progress.
The bottom line is that we are able to deliver a significant reduction in load times for quite a variety of different websites.