"The experiment confirmed that usage of minified code is extremely popular on the web as it exists and amongst others, UglifyJS is very commonly used in today's web. So in Windows 10 and Microsoft Edge, we've added new fast paths, improved inlining and optimized some heuristics in Chakra's JIT compiler to ensure that minified code runs as fast, if not faster than the non-minified versions. With these changes, the performance of individual code patterns minified using UglifyJS that we tested, improved between 20-50%."
As you can see, Edge blows IE away and also beats Chrome and Firefox. The browser team also used Apple's Jet Stream benchmark and got similar results:
The blog states:
Source: Microsoft Edge blog