bug#15555: 24.3; Bidirectional display very slow with long lines

[Eli Zaretskii]

> Date: Tue, 18 Feb 2014 18:01:05 +0400
> From: Dmitry Antipov <dmantipov@yandex.ru>
> CC: 15555@debbugs.gnu.org
> 
> On 02/18/2014 04:43 PM, Dmitry Antipov wrote:
> 
> > Are you sure that bidi_copy_it doesn't add one more bottleneck to the whole
> > stuff?
> 
> There is a busy bidi_shelve_cache/bidi_unshelve_cache loop which processes
> ~1.5M of cache data per each iteration.

Where's that loop in the sources?

> That's why memcpy takes ~25% in the overall profile...

Why doesn't this happen in the other (smaller) file?