If all pages were static this would’ve worked beautifully. But they aren’t, and uBO approach also implies that there is a mutation observer constantly monitori

If all pages were static this would’ve worked beautifully. But they aren’t, and uBO approach also implies that there is a mutation observer constantly monitoring DOM changes and adding new rules when they are needed. In a browser extension it uses browser’s own RPC to pass DOM nodes to the background page, check them, and apply new rules when needed. In our case we would’ve needed to use something like a websocket to do it, but WS may be quite problematic. And the overall performance gain from this DOM-survey approach is milliseconds, it’s not something that a person can notice.