This part is not realistic if it's apples to apples. Performance will always drop because the high performance came specifically by doing unsafe things that enable attackers. Adding checks or restrictions slows it down. The question is whether it can be done without slowing things down too much. I'm hopeful about this given many people are comfortably using their PC's and the net on 8-year old PC's w/ Core Duo 2's that still run pretty well. That was 65nm tech. Matching it or at least a smartphone is what I'd aim at for first run.
No, this is not true. Strong static typing and other compile-time information can (at least theoretically) allow improving both security and performance.
For example, look at single address space operating systems. Switching between security domains is cheaper when you don't have to switch address spaces. That's an improvement to security that allows increased efficiency.
Every time I read about it I wonder how things would have turned out, if they managed to do a proper job with the CPU.
If we had a way to implement a capability-secure runtime on Linux on Intel CPUs, in a way that improved performance rather than making it worse, and was straightforwardly usable with existing programs, then we could make a ton of progress and easily be commercially successful.
But that is technologically difficult. Maybe we can still figure it out, though. Or maybe we just need to figure out the right trade-offs to get something viable out the door and widely used.