I use and like the breadcrumb ELPA package.

  https://elpa.gnu.org/packages/breadcrumb.html

It's installed/enabled using:

--8<---------------cut here---------------start------------->8---
(use-package breadcrumb
  :ensure t
  :init (breadcrumb-mode 1))
--8<---------------cut here---------------end--------------->8---

Now when I find the attached mirrorstatus.json using json-ts-mode (that
seems to be important), set point on the first { and insert some spaces,
Emacs will eventually freeze for several seconds or even minutes.

It can be reproduced with

  emacs -Q
  M-x package-initialize RET
  M-: (package-activate 'breadcrumb) RET
  M-x breadcrumb-mode RET

and then finding the file and doing as written above.

I've also attached a gdb backtrace which suggests that emacs is
collecting garbage (produced by the breadcrumb ELN code)?  I've also
tried profiler-start, reproduce the freeze, wait for it to go away,
profiler-report.  That said that 99% of cpu time where spent in
Automatic GC.

I currently have no emacs without native compilation handy so I cannot
tell if that's important, too.  Can I somehow tell emacs not to compile
breadcrumb natively after deleting the eln file?