wasm-overhead-research/README.md

JavaScript to WebAssembly Compilation: Performance Analysis

Executive Summary

Optimal choices by use case:

• Minimal size (< 10KB): AssemblyScript - 8.2KB gzipped
• Balance (< 100KB): Porffor - 75.1KB gzipped (9.1x larger than smallest)
• Full JS compatibility: QuickJS - 265.5KB gzipped (32.3x larger, Wasmer/Extism compatible)
• Avoid: Go+Goja - 3.6MB gzipped (445.7x larger than AssemblyScript)

Size Comparison (Actual Measurements)

Data location: results/size-comparison.csv

Implementation	Raw WASM	Gzipped	Compression	Overhead vs Smallest
AssemblyScript	18.4KB	8.2KB	55.5%	Baseline
Porffor	512.9KB	75.1KB	85.3%	9.1x
QuickJS	633.1KB	265.5KB	58.0%	32.3x
Go Basic	2,791KB	835KB	70.1%	101.8x
Go + Goja	15,571KB	3,657KB	76.5%	445.7x

Note: TinyGo builds failed during benchmarking but typically produce ~128KB gzipped binaries

Runtime Compatibility Matrix

Implementation	Wasmer	Extism	Node.js	Browser	WASI	Requirements
AssemblyScript	✅	✅	✅	✅	❌	None
Porffor	⚠️	⚠️	✅	✅	❌	Legacy exceptions
QuickJS	✅	✅	✅	❌	✅	WASI runtime
Javy	✅	✅	✅	❌	✅	WASI runtime
TinyGo	❌	❌	✅	✅	❌	wasm_exec.js
Go Basic	❌	❌	✅	✅	❌	wasm_exec.js
Go + Goja	❌	❌	✅	✅	❌	wasm_exec.js

WebAssembly Compilation Performance

Based on actual measurements from simple-benchmark.js

Implementation	Cold Start (ms)	Status
AssemblyScript	0.28	✅ Fastest
Porffor	Compilation fails	❌ Invalid branch depth
QuickJS	1.16	✅ Good
Go Basic	~2-3	✅ Acceptable
Go + Goja	~5-10	⚠️ Slow

JavaScript Feature Support

Feature	AssemblyScript	Porffor	QuickJS	Javy	Go+Goja
ES5	Partial	✅	✅	✅	✅
ES6+	Partial	Partial	✅	✅	✅
async/await	❌	❌	✅	✅	✅
eval()	❌	❌	✅	✅	✅
Regex	Limited	✅	✅	✅	✅
JSON	✅	✅	✅	✅	✅
TypeScript	✅	❌	❌	❌	❌

Build Commands

# Install dependencies
npm install
rustup target add wasm32-wasip1

# Build specific implementation
mise run build:assemblyscript      # 8.2KB gzipped
mise run build:porffor:optimized    # 75.1KB gzipped
mise run build:quickjs              # 265.5KB gzipped
mise run build:basic:go:optimized   # 835KB gzipped
mise run build:goja:go:optimized    # 3.6MB gzipped

# Build all
mise run build:all:optimized

# Measure sizes
./measure-sizes.sh > results/size-comparison.csv

# Run benchmarks
node simple-benchmark.js

Implementation Specifications

AssemblyScript (8.2KB gzipped)

• Compiler: asc 0.27.0
• Target: wasm32
• Build time: 3s
• Strengths: Smallest size, TypeScript support
• Limitations: Limited JavaScript compatibility

Porffor (75.1KB gzipped)

• Compiler: Porffor 0.53.1
• Mode: AOT compilation
• Build time: 2s
• Strengths: Good size, AOT optimization
• Limitations: Compilation issues in some runtimes

QuickJS (265.5KB gzipped)

• Engine: QuickJS 2024-01-13
• Wrapper: Rust 1.83.0
• Target: wasm32-wasip1
• Build time: 45s
• Strengths: Full JS support, Wasmer/Extism compatible

Go Basic (835KB gzipped)

• Compiler: Go 1.24
• Target: wasm32
• Build time: 8s
• Runtime: Requires wasm_exec.js (16KB)
• Limitations: No Wasmer/Extism support

Go + Goja (3.6MB gzipped)

• Compiler: Go 1.24
• JS Engine: Goja embedded
• Build time: 12s
• Strengths: Full JS interpreter in Go
• Limitations: Massive size overhead (445x larger)

Extism Runtime Overhead

Data location: results/engine-overhead.csv

Language	SDK Size	Dependencies	Total Overhead	Architecture
Go	N/A	Pure Go	0	Native wazero
Rust	72KB	Static	Embedded	Static link
JavaScript	2.12MB	None	2.12MB	V8 native
Python	11KB	libextism	5.7MB	FFI
Java	N/A	JNA+libextism	7.0MB	FFI

Key Findings

1. Size efficiency: AssemblyScript produces the smallest binaries (8.2KB) but with limited JS compatibility
2. Porffor issues: Shows promise (75KB) but has compilation failures with invalid branch depths
3. QuickJS sweet spot: At 265KB provides full JS support with Wasmer/Extism compatibility
4. Go overhead: Go-based solutions are 100-445x larger than AssemblyScript
5. Compression rates: Range from 55% (AssemblyScript) to 85% (Porffor)

Recommendations

Use Case	Recommendation	Size	Rationale
Size-critical	AssemblyScript	8.2KB	Smallest possible WASM
General purpose	QuickJS	265KB	Full JS + Wasmer support
Node.js only	Porffor*	75KB	Good size (*if fixed)
Avoid	Go + Goja	3.6MB	445x overhead unjustified

Data Files

• results/size-comparison.csv - Actual size measurements
• results/benchmark-summary.csv - Performance metrics
• results/engine-overhead.csv - Extism runtime overhead by language
• measure-sizes.sh - Size measurement script
• simple-benchmark.js - Benchmark harness

Reproducibility

# Environment
uname -a > results/environment.txt
node --version >> results/environment.txt
rustc --version >> results/environment.txt
go version >> results/environment.txt

# Regenerate measurements
./measure-sizes.sh > results/size-comparison.csv
node simple-benchmark.js

# Verify results
sha256sum results/*.csv > results/checksums.txt