Would you rip out the guts of a modern browser and replace them with brand-new code that you claim is 25% faster? No way. You'd be laughed out of the room. How

Would you rip out the guts of a modern browser and replace them with brand-new code that you claim is 25% faster? No way. You'd be laughed out of the room. How exactly would you get a radical expansion of the attack surface past a security audit? You might do it in a game, where security is (usually) not a primary concern. Anyone who would sacrifice browser security for a 25% increase in performance is a fool. Browsers need to be secure, and then performance needs to be "good enough".