Questions tagged [performance]

is for Emacs performance-related issues. Use additional tags to indicate which aspects of Emacs the performance issue is about: startup, navigation, search, screen updates, compilation, execution, debugging, and so on.

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3
votes
1answer
217 views

Debugging open file handles in emacs

Is there a way I can find what file handles emacs has open, and close these references? Or even better, find where they are being open? Emacs is keeping handles to a large number of files (a leak) ...
2
votes
1answer
212 views

Size of process output sent to filter functions

I'm using comint to communicate with a REPL. From time to time the REPL sends large amounts of data. This causes a significant lag (about one second), because my filter function gets called on a ...
2
votes
1answer
193 views

Setting faces is slow?

I'm seeing rather bizarre behavior. I have the following code: (defun set-mode-line-face () (let ((color (pcase (random 6) (`1 '("#586e75" . "#eee8d5")) (`2 '("#...
10
votes
1answer
468 views

`looking-back` performance

I have some code using (looking-back … (line-beginning-position)). Doc string of looking-back states that it's better to avoid this function because of slowness. I'm curious will following approach ...
2
votes
1answer
214 views

auto-complete mode performance is awful in nxml-mode

Performance used to be OK, but a couple of weeks ago the performance got much worse. Some experimentation showed that it's auto-complete-mode in XML files. When I type, it now takes a second or two ...
6
votes
0answers
750 views

How to find what causes ESS to run very slow?

When working with an iESS session of R and an R file open side-by-side, I noticed extremely slow performance when typing indetifiers. Typing braces and operators is fine, however, when an identifier ...
14
votes
2answers
2k views

How to prevent slow-down when an inferior processes generates long lines?

I use Emacs with Geiser to hack on some Scheme code. As I'm playing around in the REPL I sometimes evaluate expressions that result in a lot of output, often all on one line. For example, I just ...
42
votes
1answer
14k views

How can I troubleshoot a very slow Emacs?

I am writing a document and I have a problem with Emacs' performance that I think appeared just yesterday. I haven't made any alterations in my init file or installed any new packages. The problem is ...
13
votes
2answers
2k views

practical limits on org-mode file size?

I have an org-mode file that's running around 6,000 lines with a hundred or so top-level headlines. It's started to take around a minute to load or save, and occasionally it sends emacs into the weeds ...
8
votes
1answer
1k views

“Making tag completion table” Freezes/Blocks — how to disable

TLDR: I've got a large tags file that loads multiple times per session, making it unusable. Can't find the source of issue or how to disable it -- main goal is to jump to tags, but completion would ...
24
votes
1answer
2k views

What algorithm does sort use?

I need to add a single integer to a list that's already sorted, such that it goes in the right place. My first tought was something like (sort (cons newelt list) #'<) However, given that list is ...
31
votes
3answers
2k views

Why is `let' faster with lexical scope?

While reading through the source code for the dolist macro, I ran into the following comment. ;; This is not a reliable test, but it does not matter because both semantics are acceptable, tho one ...
6
votes
1answer
338 views

What are the advantages of building Emacs from source?

I use precompiled Emacs binaries (24.3) right now. AFAIK, v24.4 is already available as binaries, so there is no incentive for me to compile Emacs myself to stay current. I'm thinking, however, ...
10
votes
1answer
196 views

Are there any pre-existing benchmark suites for Emacs itself?

(This question is not about writing benchmarks/profiling elisp code, for that, see this question.) Do any benchmark suites exist for Emacs performance? I'm looking for something equivalent to the V8 ...