The issue asks to reduce formatting time from ~2 seconds for 400 files to half that. No specific bottlenecks are identified. To start, profile the current code using GHC's profiling tools (e.g., run with +RTS p) to identify slow functions. Look at the main formatting loop in src/Format.elm or similar. Check if there are any redundant traversals or inefficient data structures. Consider parallelizing independent file formatting. The issue has 9 comments; review them for any prior investigation or suggestions.
