Diffing commits of big files is slow

[Alexander Belchenko]

Daniel Clemente пишет:
> In a pack-0.92 branch with latest Bazaar (1.17dev), I replaced a 40 Mb video with a newer version (30Mb). 
> 
>   I am intrigued as to why the following operations are so slow:
> 
> - at the GTK interface (bzr vis), click on that particular revision to see the diff. An strace revealed that Bzr was comparing lots of binary data
> 
> - bzr diff -r 40: it stops some seconds until it can say: === modified file 'videos/Patata.ogg'. Binary files videos/Patata.ogg	2009-06-18 21:29:07 +0000 and videos/Patata.ogg	2009-06-21 22:45:25 +0000 differ
> 
>   The two videos are clearly different right in the headers, so testing for inequality could be instant. What else does Bazaar do and why is this favorable to the user?
> 
>   Format 2a has also this non-instant diff.

Can you check `bzr qdiff`?