(This is sparked partially by the discussion of how Kryptonite affects Clark differently . )

What if when Clark escapes the Kryptonite cage in HoL, his powers return as quickly as they do in Madame Ex? What if he *can* physically save Lex Luthor as he falls from the sky? What would he do? How would this change things? Would he even be able to get away to change back into Superman? In the original scene, he seems prepared to just fly as is and go straight at it.

And also, has this idea ever been done before?

No one but Lois was paying attention to Clark. If he was at full speed, he might be able to pull off a save with only Lois finding out. He could step away from her and fly off, changing in mid-air, and grab Lex. If he has enough time, he could zip around the corner before he changes so that it's less likely that anyone will notice that he came from the crowd, but he might not think of that.

I don't remember Clark ever doing a speed-change mid-air on the show, but that has been a regular in his repertoir in other portrayals.

There were lots of times when Clark jumped down (from a balcony at the Planet, from an airplane, from a helicopter) and changed in mid-air before catching Lois as Superman. I don't recall him ever jumping up from the ground as Clark and then changing in mid-air, though.