[Fix]: Don't mark all lines in buffer as dirty, only visible lines

[sandersantema]

In the original code all of the lines in the current buffer are marked as dirty. I don't know whether filetypes which have treesitter support suffer from this too but for a big buffer and a filetype such as xml this gets very slow to the point where it blocks neovim for a while until it's done. This happens too after the latest performance commits but I don't know if they were relevant.

This pr is a simple change which makes it so that only the currently visible lines in the buffer are redrawn. I'm opening this pr as a draft because I'm only using a very limited subset of this plugin's features so I don't know if anything besides simply highlighting is impacted by this. Consider it a issue report with an included preliminary fix.

If you're interested I've got a stack trace too, although the only thing it really shows is todo-comments.highlight.match being called 45000 times for every line of my large xml document.

Other than that, hartstikke bedankt for all the fantastic work Folke! Greetings from up north :)

[sandersantema]

I believe you might have intended last to be:

last = math.min(last + Config.options.highlight.multiline_context, vim.api.nvim_buf_line_count(buf))

Instead of:

last = math.max(last + Config.options.highlight.multiline_context, vim.api.nvim_buf_line_count(buf))

Otherwise last would always have a value equal to the line count of the buffer or larger.

[folke]

omg, inderdaad! Stomme fout van mij :)

Net gefixed.