gcmh VS lsp-mode

cf. https://github.com/emacsmirror/gcmh (the author's [=Andrea Corallo's] Emacs package "GCMH - the Garbage Collector Magic Hack")

A lot of people use way higher values than 800 KB without any problems. As a matter of fact, I've been using 256 MB for a very long time, haven't noticed any issues with it. So I wouldn't call 1 GB madness, it can be perfectly fine in some cases, especially if one uses gcmh, so it has a high chance that GCs will happen when the user doesn't interact with emacs (I also setup emacs to do GC when emacs loses focus. This means that GC pause is invisible most of the time for me). I strongly prefer very rare, short GC pauses than microstuttering all the time. Also, some operations apply a lot of pressure to the memory system, and do hundreds of GCs with the default setting, so most of the CPU time is spent in the GC when these operations run. Increasing gc-cons-threshold makes such operations much faster which means less pauses.

One possible solution is to switch to a LSP approach. You should also take a look at the garbage-collector-magic-hack package: https://github.com/emacsmirror/gcmh

If you experience some lag, my first advice would be to install the GCMH package. It basically changes the garbage-collection rules to ensure that most garbage collection will happen in small bouts while Emacs is idle. After installing it I've never had my Emacs lag on me. This wouldn't address the retina-display issues you mentioned, but I've never experienced those with emacs-plus.

I've seen gcmh recommended as a library that configures the garbage collector for you. Not sure if it is truly a "one size fits all" solution though.

I’d add that for 1) beacon is a good package. For 2), this may be an issue where you have multiple emacs configuration files. This is a serious problem. 3) be patient, and use the magic GC hack. To add to that, you should probably set the GC threshold to be high. 4) projectile? 5)emacs -nw.

I also tried to the solutions suggested  and , but nothing worked. I moved the (setq lsp-keymap-...) line outside (and before) use-package. I also used :config (define-key lsp-load-map...) in my use-package block. But none of them worked.

Not sure how much this might help, but lsp-mode has lsp-yaml-select-buffer-schema and lsp-yaml-set-buffer-schema commands to pick schema from a list or set from a URI. Checking the source of them might give some hints about how the same could be implemented in eglot?

Beyond that you might as well embrace the suck and install autex with a language server: https://emacs-lsp.github.io/lsp-mode/

Smart completion these days is done primarily through LSP. eglot is fairly minimal but built-in as of 29, also available via GNU Elpa. lsp-mode is another option with more integrations and a bit more fleshed out.

lsp-mode: https://github.com/emacs-lsp/lsp-mode/issues/2080

Are you running emacs-29? It has numerous speed-ups compared to emacs-28 and older versions, many of them coded by Mattias Engdegård, e.g. commit def6fa4246. I have a fresh build of emacs-29 running on Linux and a new mac with an M1 CPU, and it's stupid fast. I don't use the native-comp feature. I rarely notice any hesitation or slowness. I don't use Elpy. I do use lsp mode.

Since you are doing code development, the first things to go for would be setting up your emacs packaging (installing use-package and melpa (use-package's documentation covers this) so you have more packages to choose from (do be careful to not just pick things willy nilly but research them a bit first)) and then setting up lsp-mode. lsp-mode lets you use LSP servers for the specific programming languages you work with in a somewhat unified fashion. You then need to install and setup the LSP servers for the languages you use, and possibly install language specific Emacs packages as support (note, Emacs has builtin functionality for many).

And first of all, I'm trying to understand, how is it connected to https://github.com/emacs-lsp/lsp-mode? I'm sure, that existed lsp implementations already parse source code. Why TreeSitter?