Ask HN: How do you review large changesets?

When code branches get large enough (>= 4k LoC), I feel like the only way to review them is through functional testing.

Basically, I find that I need to breakpoint each changed line, and have both the stack and the line's diff available at each breakpoint. That's the only way I can see the context of what brought me to the change from the code history and runtime contexts.

What do other people do to review large sets of changes? Have you found any good ways to make both the code-history and runtime context changes available while debugging?

(On a more practical note: are there any good ways of going from a diff to a list of breakpoints in VS?)