They did note that the JavaScript benchmarks were reduced by upto 58%, while noting that users won't generally notice the difference.

I would be interested to see how this affects the performance of websites that make use of complex JavaScript for things like charting/visualization (like the D3.js demos, or online formulae graphing tools), audio waveform rendering/processing, games, and other complex uses of JavaScript (including things like vue, react, bootstrap or other JavaScript UI frameworks).