So there's two reasonable strategies. One is to maximize the score per action by doing the mental arithmetic to determine whether you can still add the current number to the larger number and maximize the diff, or whether you need to add it to the smaller one. The other is to simply maximize the number of actions by always clicking on the smaller of the two numbers which requires much less cognitive effort.

I tried both strategies, and on clean runs got scores of 266 (maximize score per action) and 270 (maximize action count). It's a bit unsatisfying that the dumb strategy can be effective. I think you'd need to be only about 30% faster when executing the simple action than the complicated one to break even.

Maybe it'd make sense to make the scoring rule non-linear? E.g. instead of 0/2/4/6/8 points give 0/1/2/4/8.