Profiling - Difftastic Manual
Description: The official manual for difftastic, the syntactic differ

## Profiling

If you have a file that's particularly slow, you can use cargo-flamegraph to see which functions are slow.

    $ CARGO_PROFILE_RELEASE_DEBUG=true cargo flamegraph --bin difft sample_files/slow_before.rs sample_files/slow_after.rs

It's also worth looking at memory usage, as graph traversal bugs can lead to huge memory consumption.

    $ /usr/bin/time -v ./target/release/difft sample_files/slow_before.rs sample_files/slow_after.rs

If timing measurement are noisy, Linux's `perf` tool will report instructions executed, which is more stable.

    $ perf stat ./target/release/difft sample_files/slow_before.rs sample_files/slow_after.rs
    $ perf stat ./target/release/difft sample_files/typing_old.ml sample_files/typing_new.ml

Many more profiling techniques are discussed in The Rust Performance Book.