Mattias Engdegård <mattias.engdegard@gmail.com> writes:

> 3 juni 2024 kl. 19.37 skrev Thierry Volpiatto <thievol@posteo.net>:
>
>>      (with-temp-file file
>>        ;; Fix Emacs-30 lexbind warnings. 
>>        (insert ";;; -*- lexical-binding: t -*-\n")
>>        (prin1 `(setq-default ,obj (eval-when-compile ,obj)) (current-buffer)))
>>      (byte-compile-file file)
>
> We have made small changes to several of the moving parts here but it's unclear how they have the outsized effect you reported.
>
>> Perhaps this commit?
>
> I wish! But it could be useful to find what actually did. If you had
> the time to bisect master to find it,

I finally found:

--8<---------------cut here---------------start------------->8---
;; ae8f815613c  Sun Mar 24 14:37:03 2024 Update files for Emacs 29.3 Eli Zaretskii  (tag: emacs-29.3)
(benchmark-run 1 (psession--dump-object-to-file-save-alist))
(8.715188143 0 0.0)
--8<---------------cut here---------------end--------------->8---

--8<---------------cut here---------------start------------->8---
;; 83a6e80d66a  Mon Mar 25 03:13:44 2024 (byte-optimize-form-code-walker): Simplify a bit Stefan Monnier 
(benchmark-run 1 (psession--dump-object-to-file-save-alist))
(0.259306895 0 0.0)
--8<---------------cut here---------------end--------------->8---

So it is the first change after emacs-29.3 tag, done by Stefan, even if
small, it makes a huge difference as you can see above (not sure to
understand why though :-)).

--8<---------------cut here---------------start------------->8---
diff --git a/lisp/emacs-lisp/byte-opt.el b/lisp/emacs-lisp/byte-opt.el
index f6df40a2d9b..54997205edb 100644
--- a/lisp/emacs-lisp/byte-opt.el
+++ b/lisp/emacs-lisp/byte-opt.el
@@ -482,9 +482,6 @@ There can be multiple entries for the same NAME if it has several aliases.")
          (push name byte-optimize--dynamic-vars)
          `(,fn ,name . ,optimized-rest)))
 
-      (`(,(pred byte-code-function-p) . ,exps)
-       (cons fn (mapcar #'byte-optimize-form exps)))
-
       ((guard (when for-effect
 		(if-let ((tmp (byte-opt--fget fn 'side-effect-free)))
 		    (or byte-compile-delete-errors
--8<---------------cut here---------------end--------------->8---


-- 
Thierry