(Partial) Ref # A Dictionary of Advanced Japanese Grammar p141
Kanzen Master has this listed under ~たところで, which apparently on it's own can also express that the first part of the sentence would be a wasted effort, e.g. 約束の時間にこんなに遅れては、行ってみたところで、だれもいないだろう (what with it being so late after the agreed time, even if I went now, surely there'd be no one there.)
さらに really emphasizes how late in the day such an ineffective action would be. Nevertheless, keep in the back of your mind that たところで can exist on it's own with a similar meaning. On past test papers I've had questions that lead with さらに and the correct answer they wanted for the blank that came after was たところで so maybe it's worth learning these as a pair, this will also help you distinguish it from [toshitatokorode toshitatte nishitatokorode] etc. which has a slightly different nuance meaning even though the first part of the sentence is NOT a wasted effort, the final result doesn't satisfy.
For reference, Dictionary of Advanced Japanese Grammar has this listed under さらに, key sentence D
They are almost the same. 今頃になって説明したところで、…。 今頃になって説明したって、…。
ex#3980 can be also said as 今さら騒いでもどうにもならないよ。…。
not sure how this is different from [imagoroninatte]
A better translation would be " Even if (one) had 〜ed now, ... still ..."
I agree with 誠. ex#3980 translation makes more sense as: "Even if you make a fuss now, nothing can be done (about it). It's too late!"
I sometimes hear the slang version without the ところで at the end, for example: 「いまさら言うなよ」