[otherjason]

Difftastic is a useful tool, but in my experience, it's far too slow to be suitable as the default selection for a ubiquitous tool like git.

[drcongo]

I'm finding it instantaneous here on a large dirty codebase. In what way is it slow for you?

[acdha]

Diff a large JSON file - I think it has to do with how large a single structure since I notice it most with static test fixtures.