Very Slow on large-ish diff files

[MasterOfGrey]

So I got this extension specifically because I received a .diff file I wanted to view in a way that was better on my eyes and nothing else really seems to do that specific job.
(Lots of things that diff two files, or interact with repos, but not a lot that will just parse a pre-existing standalone diff file.)

However, I couldn't get the diff file (7mb) to actually open in side-by-side mode, and it was really struggling with line-by-line mode.

I know it's using diff2html under the hood - is there some way to improve performance? Does it all run locally, or perhaps should it?

[caponetto]

Thanks for reporting! Since this extension is just a wrapper around diff2html, performance is limited by that library itself. There's an open discussion on this in diff2html#520 about a lazy-loading approach, though it hasn't seen recent activity. That's the best place to follow or contribute ideas.

[jacekkopecky]

@MasterOfGrey out of curiosity, is it a diff of a single pair of huge files, or maybe many files, where any one of them on its own would be manageable?

diff-viewer might be able to handle a big multi-file diff it if it started with all files collapsed. I might be able to contribute a PR for that as a new command, for example.

[MasterOfGrey]

@jacekkopecky I checked and yeah it's a diff export of many files where individually it would be fine.
I got given it as a reference for working on something, I didn't create it.

Starting with all files collapsed sounds like a good way to go.

[jacekkopecky]

@MasterOfGrey cool, I have a weekend project then; can't say how far I'll get with it.

[jacekkopecky]

@MasterOfGrey the new command in #125 may help, but it still has to compute the whole HTML for the diff at once, it just avoids trying to show it all.

It's possible that your situation can be handled better by manually splitting your huge diff file in a normal text editor into smaller, more-manageable chunks. Split before any line starting with +++ or ---, whichever comes first, without leading spaces.