I think by "performance" he was referring to hardware performance. So, beefier hardware is not necessary for today's applications, but might enable applications we can't even run (on current hardware) yet.
Exactly right. We haven't even remotely invented everything a PC can do, its not just about dotting the i's and crossing the t's of the interfaces at this stage.
Software with higher performance hardware is destined to get much smarter than it is today and a lot of things we have moved server side or run asynchronously can be run realtime.
Who is saying that increasing performance by coming up with more efficient software is useless?