I'm not actually convinced that subjective speed is what matters. It seems like what matters more is how much computation is happening per unit of time, which seems highly related to economic growth, even in human economies (due to population growth). 

I also think AIs might not think much faster than us. One plausible reason why you might think AIs will think much faster than us is because GPU clock-speeds are so high. But I think this is misleading. GPT-4 seems to "think" much slower than GPT-3.5, in the sense of processing fewer tokens per second. The trend here seems to be towards something resembling human subjective speeds. The reason for this trend seems to be that there's a tradeoff between "thinking fast" and "thinking well" and it's not clear why AIs would necessarily max-out the "thinking fast" parameter, at the expense of "thinking well".