Other browser vendors needed to overhaul their interpreters to compete. Apple developed the Nitro engine for its Safari browser, which had 30% better performance than its predecessor. Mozilla leveraged portions of Nitro to improve its own SpiderMonkey engine.
Since 2017, these engines have added support for WebAssembly. This enables the use of pre-compiled executables for performance-critical portions of page scripts.
Further information: List of ECMAScript engines