No they don't, and that's probably impossible and even with 100% efficiency that's still not anything spectacular. What they can do is to make faster cpu's. Instead of 7nm 7w limited SOC from Ipad Macs will use 5nm hp-process made two generations younger cpu with more relaxed power limits which could easily be twice as fast. With twice as fast as 12Z cpu emulated x86-speed will be at least as fast as Intel offerings - probably even faster. And that's emulated performance, for native ARM-binaries will be way faster than anything Intel can offer.But jumping to conclusions that it must be rosettas fault, and that no way in hell it may be more than 80% of performance efficiency, is way to premature, considering what Apple wants to achieve. If they want to migrate their whole platform, they have to offer at least 90% of performance in Rosettas compiler.