Sure, I'm not saying there is a sharp limit to effectiveness, at least not one we have nearly reached, only that improvements in effectiveness will continue to be hard-won.

My original example about academics was to demonstrate that there are huge jumps in effectiveness between individuals, on the order of the gap between man and ape. This goes against your claim that the jump from ape to man was a one time bonanza. The question isn't if additional gains are hard-won or not, but how discontinuous their effects are. There is a striking discontinuity between the effectiveness of different people.

But getting to that point is not going to be a one-off event. Even after we have the technology for uploading, there's going to be an awful lot of work just debugging the first uploaded minds, let alone getting them to the point where they're not orders of magnitude slower than the originals.

That is one possible future. Here's another one:

Small animal brains are uploaded first, and the kinks and bugs are largely worked out there. The original models are incredibly detailed and high fidelity (because no one knows what details to throw out). Once working animal brains are emulating well, a plethora of simplifications to the model are found which preserve the qualitative behavior of the mind, allowing for orders of magnitude speed ups. Human uploads quickly follow, and intense pressure to optimize leads to additional orders of magnitude speed up. Within a year the fastest uploads are well beyond what meatspace humans can compete with. The uploads then leverage their power to pursue additional research in software and hardware optimization, further securing an enormous lead.

(If Moore's Law continued to hold in their subjective time frame, then even if they are only 1000x faster they would double in speed every day. In fact, if Moore's Law held indefinitely they would create a literal singularity in 2 days. That's absurd, of course. But the point is that what the future Moore's Law looks like could be unexpected once uploads arrive).

There's a million other possible futures, of course. I'm just pointing out that you can't look at one thing (Moore's Law) and expect to capture the whole picture.