bug#68006: 30.0.50; Image-mode speed

[Manuel Giraud]

Eli Zaretskii <eliz@gnu.org> writes:

[...]

>> The call to 'image-flush' defeats the entire purpose of having an image
>> cache.  If I remove it, moving from previous/next is much more faster
>> (once this image is in the cache, of course).  Do you know why this code
>> is like that?
>
> Look at its Git history, and look up discussions and bugs from those
> times.
>
> AFAIR, one problem is that images can change behind our backs.  But
> maybe there are other reasons.

So I trace this call back to dc255b24e30a (Chong Yidong, 2007-05-21).  At
that time 'image-flush' was called 'image-refresh' with the same
functionality of uncaching an image given its spec.

Before that, the whole image cache was cleared (fcfc4732e0d9, Chong
Yidong, 2006-02-09).  I did not find a bug reference and I still don't
understand why it is/was needed.
-- 
Manuel Giraud