We are at 5nm a silicon atom is like 0.5 or 0.2 nm election tunneling is already a issue but soon enough cpus will be 3d meaning they hit 1nm in 10-15 years they will just stack cpu cores vertical until we hit a heat disapation limit, or we just create very large spread out cpus that flip bits really slowly but because its so big by the time the bits cool off your computing at normal human speeds.

But yeah basicly we are hiting a limit, also software these days is pretty inefficient so we could get speed back by rewriting code.

This is what your looking for on actul computational limits if your interestedhttps://en.m.wikipedia.org/wiki/Landauer%27s_principle