Some linters have a high startup cost, such that the time required to start the external tool are unproportionally high compared to the amount of time required to actually lint the file contents. A good example is ESLint, which has been reported internally to be nine times slower when run through arc lint compared to running eslint directly.

I think that the best solution here is to allow paths to be passed to external linters in batches.

This needs some more work, but I wanted to know what @epriestly thought before I continued working on it. With a batch-size of 20, the time required to run arc lint on 60 JavaScript files reduced from 30 seconds to 7 seconds locally.