TJS Benchmarks

Generated: 2026-08-19 Runtime: Bun 1.3.14 Platform: darwin arm64 Iterations: 100,000 per test

Summary

Benchmark	Baseline	Safe (default)	Unsafe (!)
CLI: Bun + TypeScript	45.5ms	-	-
CLI: tjsx (execute TJS)	41.3ms	-	-
CLI: tjs emit	42.8ms	-	-
CLI: tjs check	43.1ms	-	-
Simple arithmetic (100K iterations)	0.4ms	0.6ms (1.5x)	0.4ms (~1.0x)
Object manipulation (100K iterations)	0.4ms	0.7ms (1.7x)	0.5ms (1.1x)
3-function chain (100K iterations)	0.4ms	0.8ms (2.0x)	0.4ms (0.9x)

Key Findings

CLI Cold Start

Bun + TypeScript: ~46ms (native, baseline)
tjsx: ~41ms (includes TJS transpiler load)
Overhead: none measurable — tjsx starts as fast as plain Bun

Loading the acorn parser and the TJS transpiler costs less than the run-to-run spread of this measurement, so it does not show up as startup cost.

Safe vs Unsafe Functions

TJS functions are safe by default with runtime type validation. Use (!) to mark functions as unsafe for performance-critical code:

// Safe (default) - validates types at runtime
function add(a: 0, b: 0): 0 { return a + b }

// Unsafe - no validation, maximum performance
function fastAdd(! a: 0, b: 0): 0 { return a + b }

Performance comparison:

Simple arithmetic: Safe 1.5x vs Unsafe ~1.0x
Object manipulation: Safe 1.7x vs Unsafe 1.1x
3-function chain: Safe 2.0x vs Unsafe 0.9x

Recommendations

Use safe functions at API boundaries - The default is correct for most code
Use (!) for internal hot paths - When inputs are already validated
Consider compiled binary for CLI - bun build --compile for ~20ms startup

Running Benchmarks

bun run bench

Or run the test suite with timing output:

bun test src/lang/perf.test.ts