Subject: bug#66117: 30.0.50; `find-buffer-visiting' is slow when opening large number of buffers

From: Dmitry Gutov <[email-masked]>
Date: Tue, 12 Dec 2023 22:47:35 +0200

On 12/12/2023 22:01, Stefan Monnier wrote:
> This said, in the case of `case-fold-search` I think there's a simpler
> solution: make it "buffer-local only", meaning that let-binding it
> affects only the current buffer (rather than affecting all the buffers
> which have not made it buffer-local yet).

Wouldn't that be a breaking change? And a non-obvious one.

E.g. company-dabbrev-code creates a dynamic binding for case-fold-search 
in one place and then calls a function (company-dabbrev--search) that 
iterates across all buffers with re-search-forward.