Re: Redisplay slower in Emacs 28 than Emacs 27

[Lars Ingebrigtsen]

Eli Zaretskii <eliz@gnu.org> writes:

>> +    case Lisp_String:
>> +      val = (EMACS_UINT) SSDATA (obj);
>
> Why use the pointer?  Lisp strings can be relocated, and there could
> be another string with the same contents.  Why not support those?

Yes, that's not a good ID for the string.  What's the proper way to get
the identity of the string object?

>> -  while ((img = search_image_cache (f, spec, sxhash (spec), 0, 0, true)))
>> +  while ((img = search_image_cache (f, spec, img_hash (spec), 0, 0, true)))
>
> Any reason you call img_hash in a loop with the same argument?

It's not me; it's search and replace.  And, no, there's no reason why
the sxhash in in that loop; it should be fixed regardless.

> Last, but not least, a question: what kind of savings will this
> produce, and why?

It depends on many different things, but between 0% and 20% in my test
cases.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no