Performance issue on diff with 40k lines

[jumper047]

Title says it all - recently I faced really big diff, like 40k lines changed, and magit buffer became completely unusable. I disabled magit-delta mode, and everything became usable again. Maybe we should have something like magit-delta-max-diff-size parameter?

[dandavison]

Hi @jumper047, yes I sympathise with this. I'd be happy to review a PR.

[jumper047]

@dandavison done:)

[igorcafe]

Same problem here.
I think the diff should be lazy loaded when we press tab here, instead of loading automatically as I guess its doing.
Is it possible to do in magit?

Here, I think its loading this retroarch configs that are huge and I'm not even seeing it, and its very laggy