We therefore rebuilt our ad-blocker taking inspiration from uBlock Origin and Ghostery’s ad-blocker approach. This focuses on a tokenization approach specific to ad-block rule matching against URLs and rule evaluation optimised to the different kinds of rules. We implemented the new engine in Rust as a memory-safe, performant language compilable down to native code and suitable to run within the native browser core as well as being packaged in a standalone Node.js module. Overall, we found that:
- The new algorithm with optimised set of rules is 69x faster on average than the current engine.
- For the popular filter list combination of EasyList and EasyPrivacy it achieves class-leading performance of spending only 5.7μs on average per request.
- An additional benefit of having the blocker built into the core of the browser is even less work duplicating what the browser already does, e.g. for URL parsing. With this information already available, our browser-focused API provides still better performance, cutting average request processing time down to 4.6μs.
- The new engine already supports more of the filter rule syntax that has evolved beyond the original specification, which will allow us to handle web compatibility issues better and faster.
