emacs really slow when inserting a new source code block

[Luca Ferrari]

Hi all,
I'm having issues in my org files whenever I insert a new source block
(perl if that matters) with "#+begin_src perl" Emacs becomes really
slow.
I can move, paste, edit within the source block (in the same org
buffer, not an external window) but at a very slow rate.
In the messages I've only this:

Starting new Ispell process aspell with default dictionary...done
Error enabling Flyspell mode:
(No Ispell process to read output from!)

This puzzles me because the language of my org document is set to
"it", but I never found such a big problem before.
I've tried other type of source blocks, and while they appear to
behave smoothier, whenever I edit "#+end_src" Emacs has a freeze, and
in fact in the screen I see only "#+end_s" and after a second the line
completes.

I'm running GNU Emacs 28.2 (build 2, x86_64-pc-linux-gnu, GTK+ Version
3.24.20, cairo version 1.16.0) with org-mode 9.5.5.

Anything I can inspect?

Thanks,
Luca