Syntax highlighting takes 25s~ to start working

[sammcj]

I've noticed that syntax highlighting doesn't work for the first 25 or so seconds after starting macdown

[ross-w]

Yes, I'm also experiencing this

It seems to be a delay after opening some files. The delay seems to be fairly consistent.

It's even reproducible on the help.md file shipped with MacDown

[uranusjr]

I’ve done some investigation, and the underlying problem is pretty serious. Documents with this problem take the PEG parser (which backs the highlighter) forever to parse, resulting the long delay—and a serious CPU surge while doing so. I’ll try digging into the PEG internals to fix that.

[uranusjr]

After some cross-testing it seems that the problem is the footnotes syntax. Take the bundled help.md for example, the initial highlighting takes about 0.005 seconds to parse on my machine if I remove the footnotes (there are 6), and about 30 seconds with them. Can you confirm this?

[ross-w]

@uranusjr Wow, yep. It's the footnotes alright! Can confirm the same (removing the footnotes reduces the 25-35s to nearly instant)

Didn't notice the CPU spike until you pointed it out - yes, looks like it uses 100% CPU for the duration of the rendering with footnotes.