Dmitry Gutov <dmitry@gutov.dev> writes:

> My understanding is it's due to the judicious call (copy-sequence
> orig) that you added before 'put-text-property' is called. While it
> seems like a good idea to preserve the original value, when almost all
> of obarray matches the current input (which is the current scenario),
> a lot of strings will be copied.

You're right, I reproduced the regression.  I thought I had taken out
the copy-sequence, but forgot it there.  In an earlier stage I suspected
that I needed the copy, but I don't think I do.  Please try this new
patch that removes it.  I've also pushed it to the
feature/completion-lazy-hilit branch.

João