I see. I'm not even sure how implementing ignore files in the root is trivial without, say, using 'git' directly. The gitignore format is quite subtle.
In any case, that's all fine and good, but your tool is very clearly not a clone of ag or ripgrep IMO. Whether you consider it a misfeature or not, the "smart filtering" aspect is probably the defining quality of things like ack, ag and ripgrep. So if you don't have that, I don't think you can call it a clone IMO. The smart filtering feature is right up there next to performance in terms what things users tend to like about these tools.
The other thing you're probably missing from a perf perspective, I think, is parallel directory traversal. Neither ack nor ag have this, but ripgrep does. ;-)
