Modern JavaScript APIs are growing more and more Promise heavy. It would be awesome if the benchmark suite was enhanced to cover Promise performance. One option would be to add a dedicated Promise benchmark. Alternatively the pdfjs bench could be updated to use the javascript engine's built-in Promise when available. Some links: * [Corresponding issue for Octane benchmark](https://github.com/chromium/octane/issues/35) * [Bluebird Promise benchmarks](https://github.com/petkaantonov/bluebird/tree/master/benchmark) * [jsFiddle demonstrating Promise perf issues in Microsoft Edge](https://jsfiddle.net/jdanyow/vj6o119n/) * [Microsoft Edge user voice issue](https://wpdev.uservoice.com/forums/257854-microsoft-edge-developer/suggestions/11329845-improve-promise-implementation-performance) Let me know what you think- I'm willing to work on a PR if you want to provide some direction on this.