Benchmarks and issues as of October 25, 2025. Data synthesized from recent reports and guides.
| Engine | Performance Summary (2025 Benchmarks) | LLDB Variable Resolution Issue |
|---|---|---|
| Wasmtime | High throughput (~1.4x native in managed lang backends); Cranelift JIT excels in server-side (e.g., 78% faster startup in containerized WASM vs. alternatives); strong for complex workloads but higher memory use. | Severe: Local vars show "not available" after stepping into functions/if-blocks due to DWARF lowering in JIT (open issue since 2022; affects Windows/macOS). |
| Wasmer | Balanced (~2x native); good cross-platform (browser/server); singlepass AOT for fast cold starts; ~10-20% slower than Wasmtime in CPU-bound but lighter footprint. | Minor: Occasional symbol mismatches in JIT mode, but vars generally resolve; no widespread reports—use with Emscripten for best DWARF compatibility. |
| WAMR (WebAssembly Micro Runtime) | Excellent startup (<11% slower than native in embedded); interpreter + AOT hybrid; top for IoT/low-resource (fastest in memory-efficient containers); ~3-5x native in throughput. | None/Minor: Full LLDB support via GDB-stub; vars resolve well in AOT mode (2025 guide confirms no scope loss); interpreter avoids JIT remapping bugs. |
| V8 (Liftoff/TurboFan for WASM) | Browser-dominant (~1.2x native); Liftoff baseline + TurboFan opt; fastest cold-start in JS interop; server (Node) ~15% behind Wasmtime but seamless with JS. | Minor: Optimized vars may hide, but scopes/if-vars available via DevTools/LLDB stubs; rare "no location" in aggressive opts—mitigate with -O0. |