Introduction to WebKit Content Blockers
The reason we are unhappy about the JavaScript-based content blocking extensions is they have significant performance drawbacks. The current model uses a lot of energy, reducing battery life, and increases page load time by adding latency for each resource. Certain kinds of extensions also reduce the runtime performance of webpages. Sometimes, they can allocate tremendous amounts of memory, which goes against our efforts to reduce WebKit’s memory footprint.
It is an area were we want to do better. We are working on new tools to enable content blocking at a fraction of the cost.
One new feature, we are developing allows describing content blocking rules in a structured format ahead-of-time, declaratively, rather than running extension-provided code at the moment a decision about blocking needs to be made. This model allows for WebKit to compile the ruleset into a format that’s very efficient to apply to loads and page content.
This new extension point seems to smooth over these issues in a really nice way. Not only will this improve performance, I can now have ShutUp on my iPhone, too, and block the humungous JavaScript files so many sites use these days.
