As end users, many (in fact a majority) have already made the decision that the benefits of Firefox's extensions don't outweigh the drawbacks those same extensi

As end users, many (in fact a majority) have already made the decision that the benefits of Firefox's extensions don't outweigh the drawbacks those same extensions impose on Firefox in terms of performance and responsiveness, and have voted with their feet. I appreciate that your personal tradeoff was different from most, and I know the pain of having an application that was targeting your use cases move away from that. I don't have much to offer other than the goal that Firefox still has to offer extension APIs that are broader than the ones Chrome does. It won't be quite as "yeah, hook into anything you want" as the old extension system, but that was really becoming completely unsustainable and was holding back Firefox not only in things like performance and responsiveness but also web standards: extensions would depend on things working a certain way and changing them to follow the spec would break those extensions...