That is very true! I simply think of it first because it is often the biggest problem at my work. One of the extreme exceptions was optimising Wavetale for the Nintendo Switch, where we had to decrease memory usage from over 20GiB to below 3GiB.

> <time> is actually a bit unusual as it doesn't represent an exhaustible resource.

Not in the context of game development, however! There you typically don't care about wall time. Instead, you work towards a set frame rate meaning you have a set slice of time (usually 16.7 or 33.3 ms) to go through the entire game and render loop each time.