I don't recall making a performance argument against capabilities, but I think we're conflating microkernels and capability based languages. You can have capabi

I don't recall making a performance argument against capabilities, but I think we're conflating microkernels and capability based languages. You can have capabilities without microkernels and that's often what people mean when they talk about passing caps into main(). Context switching at the hardware level does have a performance cost, so if you want to use lots of capabilities without a special programming language then you're going to pay for that yes. I don't think there are any good mainstream capability based programming languages. At least I've never seen one. Actually the SecurityManager is I think the best implementation that has existed. I've not yet seen a credible proposal that's better. Stuff like Mojo and SEL4 is at least deployed to production but that's not a programming language. > What are you even trying to do? Convince people to not explore different ideas in computer science? No. Please go read the opening of the article again, which says: "In this essay I want to show you the challenges that you’ll face if you want to walk that path. This isn’t meant to put anyone off, just to draw a map of the territory you’re about to enter and explain why it’s currently deserted." Lots of people have proposed capabilities as some silver bullet over the years, yet real systems hardly use them. Anyone who is serious about their own ideas should want to understand why that is and that's the goal of the article. It doesn't say nobody can do better! The whole point of writing it, is the hope that someone will. But to do better you have to understand why existing systems failed. It wasn't (primarily) about performance.