The Bitbucket-diff tool has a very inefficient layout. This means on my screen (a standard 3:4 screen) that I only have 50 characters per side-by-side file. This too less to be able to do a reasonable review.
Inefficiencies are pointed out in the attached image:
- Lots of superfluous whitespace. Many margins can be reduced. There seems to be a default reservation for files up to 999999 lines, but smaller files do not that that much room for line numbers
- The list of tiles subject of change is on the left. You must collapse that panel to have a screen that has enough usable space. But if you collapse it, it takes up too much space. since the information in collapsed state is zero. There also is no need to have that panel, since the information already is on top of the diff view.
As an example; Reviewboard has a more pragmatic representation, showing the file list on top and all changed files below. That also has the advantage that you can scroll through a diff instead of constantly having to switch between files manually.