Why doesn't emacs yield more?

[ndame <emacsuser@freemail.hu>]

I inadvertently pasted a huge elisp list structure into a buffer
and it took me 10 seconds or so to regain control, because emacs
was bogged down by formatting/highlighting the list I think.

It tried to hit C-g several times to no avail which made me
think: why doesn't emacs yield more during long operations by
checking if the user canceled the operation?

I don't mean putting checks everywhere manually, but using some
automatic code translator which would inject such checks
automatically in the source codes of loops or something, before
the actual compilation of emacs.

Would it be a big performance hit? I don't know if the check
could be inlined somehow. Was something like this discussed
before?


(I posted this to help, because I don't know the internal architecture
of emacs, so the question may be naive or unworkable.)