It's not super uncommon for us to have massive amounts of output logged for any given build. By "massive" I mean our median build log size is 125kb, and our largest build log to date is 31MB. p99 is sitting somewhere around 1MB.
When attempting to talk about builds and the log output, we usually just link people to the build page and give them a line number along with the step that issued it, leaving them to the awesome task of scrolling through tens of thousands or hundreds of thousands of lines of log output to find what we're talking about.
I'd propose just making it possible to page through log output on a separate display somewhere, but more importantly just being able to link to a specific line in a specific log would be helpful. Typically for requests like this I just go add my own pages to our install, but I wasn't able to cook up a good way to deal with the log output in a line-by line manner given the current software API that exposes build logs.