> The buffer is the UI, rendered by Emacs's extremely optimised text display machinery
Doesn't emacs lag like crazy in files with large lines. Why is this still a problem? Every modern editor handles this gracefully. I remember reading something about using regexes for syntax highlighting. This looks like a problem in the rendering layer which shouldn't be too hard to fix without touching the core engine. Are there any other problems that make it difficult to fix without disabling any useful features?
The problem with long lines was reportedly markedly improved in Emacs 29:
Emacs is now capable of editing files with very long lines.
The display of long lines has been optimized, and Emacs should no
longer choke when a buffer on display contains long lines. The
variable 'long-line-threshold' controls whether and when these display
optimizations are in effect.
A companion variable 'large-hscroll-threshold' controls when another
set of display optimizations are in effect, which are aimed
specifically at speeding up display of long lines that are truncated
on display.
If you still experience slowdowns while editing files with long lines,
this may be due to line truncation, or to one of the enabled minor
modes, or to the current major mode. Try turning off line truncation
with 'C-x x t', or try disabling all known slow minor modes with
'M-x so-long-minor-mode', or try disabling both known slow minor modes
and the major mode with 'M-x so-long-mode', or visit the file with
'M-x find-file-literally' instead of the usual 'C-x C-f'.
In buffers in which these display optimizations are in effect, the
'fontification-functions', 'pre-command-hook' and 'post-command-hook'
hooks are executed on a narrowed portion of the buffer, whose size is
controlled by the variables 'long-line-optimizations-region-size' and
'long-line-optimizations-bol-search-limit', as if they were in a
'with-restriction' form. This may, in particular, cause occasional
mis-fontifications in these buffers. Modes which are affected by
these optimizations and by the fact that the buffer is narrowed,
should adapt and either modify their algorithm so as not to expect the
entire buffer to be accessible, or, if accessing outside of the
narrowed region doesn't hurt performance, use the
'without-restriction' form to temporarily lift the restriction and
access portions of the buffer outside of the narrowed region.
The new function 'long-line-optimizations-p' returns non-nil when
these optimizations are in effect in the current buffer.
Right- but if you have a long line that is, for example, a JSON object, then surely it can't be properly be validated or syntax-highlighted before the entire line is scanned?
I do agree that Emacs can be slower than the terminal when handling long lines/files, although (depending on your case) this can be easily mitigated by running a terminal inside of Emacs.
Generally though, for everyday use, Emacs feels a lot snappier than VSCode.
Good point. Though for widget UIs you're typically rendering structured data you control, not parsing arbitrary text files. The syntax highlighting / validation concern applies to editing code, not to building interactive interfaces.
> Generally though, for everyday use, Emacs feels a lot snappier than VSCode.
So long mode is the best fix for this issue but it disables syntax highlighting and line numbers. Vscode can handle long lines just fine without disabling anything.
The long-line issue is real, though my statement was specifically about building UIs with widgets/overlays/text properties - not handling arbitrary files. In that context, Emacs's display engine is genuinely well-optimized: it handles overlays, faces, text properties, and redisplay regions efficiently.
When you're building a UI, you control the content. Lines are short by design (form fields, buttons, lists). The pathological case of a 50KB minified JSON line simply doesn't occur.
The long-line problem stems from how Emacs calculates display width for bidirectional text and variable-pitch fonts - it needs to scan the entire line. That's orthogonal to rendering widgets or interactive buffers.
The buffer is the UI, rendered by Emacs's extremely optimised text display machinery
The author is known in the community as a mere packager whose knowledge of the nitty-gritty derives entirely from hearsay. Perhaps he read the long-winded preamble to xdisp.c written in 1995 boasting of all manner of optimisations. But they were written so long ago, almost no one believes most of them matter anymore, what with thirty years of bitrot.
I saw him as a content creator doing some research, like pewdiepie or mrbeast. He's a good writer though. The article was a fun read.
> Your goal here is to make the best YOUTUBE videos possible. That’s the number one goal of this production company. It’s not to make the best produced videos. Not to make the funniest videos. Not to make the best looking videos. Not the highest quality videos. It’s to make the best YOUTUBE videos possible. Everything we want will come if we strive for that. Sounds obvious but after 6 months in the weeds a lot of people tend to forget what we are actually trying to achieve here.
Not even close. Claude and codex are the best git gui.
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