$ cargo build --features=lang-cjk,video-ffmpeg --release

You don't strictly have to use '--release' anymore, but it does optimize the whole thing if you do. The dependent crates are now always built in release/optimized mode (since those don't get recompiled every time you edit a line and compile again, the cost of doing it isn't borne as badly as if the main crate were optimized every time you just changed a few lines and recompiled).