> Or they think that users would rather have a faster GPT-4 than a smarter but slower one.

And they are absolutely right.

GPT-4 is already much more than enough for 90% of tasks while maintaining a sane dose of human double-checking.

Making it faster enables real-time workflows, and better energy efficiency also gives them much more capability to serve more requests/users while lowering costs. And that knowledge likely carries over to GPT-5 or whatever.