Maybe you already do it, but I think integrating adblocker functionality when loading JS sites would be desirable to reduce load time. And if ads are what the API user is interested in, perhaps add a flag for whether or not one wants ads to load.

Recommendation: https://github.com/cliqz-oss/adblocker Should be the fastest adblocker library (used by Ghostery, Cliqz and Brave)