📉 An 8× improvement in bandwidth only yields a 1.64% improvement in FCP.
📉 An 8× improvement in latency yields a 94% improvement in FCP.
🔍 Improvements in either are not guaranteed to be linear (i.e. a 10% improvement in latency != a 10% improvement in FCP; doubling bandwidth does not halve timings)
🔍 The user experience is far more tied to latency than bandwidth.
⚠️ I ran 125 tests to get this data, but it’s still only one page on one site.
⚠️ My site is already fast, so not particularly representative of the web as a whole.
⚠️ I’d expect different outcomes if there was a substantial amount of weight on the critical path (e.g. Base64—yuk!).
🍩 Most pages—hopefully—don’t weigh many MB, so extra bandwidth is superfluous. It’s like expecting a truck would be able to deliver a single donut faster than a car. It can deliver more donuts, sure, but not one donut any faster.