JavaScript Runtime Performance Analysis: Bun vs Deno 2.0 vs Node.js

Executive Summary

Performance vs stability trade-offs for JavaScript runtimes in production environments. Data from 8 months of production deployment across multiple projects.

Critical Decision Factors:

• Bun: 2.25x faster than Node.js but unpredictable production failures
• Deno 2.0: 1.5x faster than Node.js with modern tooling, stable in production
• Node.js: Predictable performance, extensive ecosystem, enterprise-ready

Performance Benchmarks (Production Workloads)

Runtime	Typical RPS	Memory Usage	Cold Start	Critical Failure Points
Bun 1.1.34	12-18k	95MB	45ms	Windows CI, Prisma crashes, Docker Alpine
Deno 2.0	8-12k	140MB	120ms	Complex npm packages, permission configuration
Node.js 22.9	6-9k	180MB	150ms	None (predictable performance degradation)

Real-World Performance Impact

• Express API Migration: Node.js 8k RPS → Bun 18k RPS (125% improvement)
• Memory Reduction: Node.js 180MB → Bun 95MB (47% reduction)
• Build Time Improvement: 45 seconds → 8 seconds with Bun
• Black Friday Load Test: Bun 48k RPS for 3 hours, then memory corruption failure

Configuration Requirements

Bun Production Configuration

Critical Settings:

• Use Ubuntu base images in Docker (Alpine Linux causes crashes)
• Prisma 5.9.1+ required to avoid segmentation faults
• Avoid Windows Server deployment entirely
• Connection pooling essential above 200 concurrent users

Breaking Point: Memory corruption at sustained high load (>40k RPS for 3+ hours)

Deno 2.0 Production Configuration

Required Permissions:

--allow-net --allow-env --allow-read --allow-write

Critical Notes:

• Permission flags required even for basic environment variable access
• JSR ecosystem smaller than npm (migration consideration)
• TypeScript works without build configuration

Node.js Production Configuration

Stability Requirements:

• LTS versions only for production
• Standard connection pooling patterns
• Mature APM integration available

Critical Failure Modes

Bun Critical Issues

1. Prisma Integration: Segmentation fault: 11 in Docker containers (Alpine Linux)
2. Windows Support: File watching system failures, random CI crashes
3. Memory Corruption: malloc(): memory corruption under sustained load
4. Header Case Sensitivity: Stripe API integration failures due to header handling differences
5. Native Module Compatibility: bcrypt, sharp, sqlite3 frequent failures

Deno 2.0 Critical Issues

1. Permission System Complexity: 2-week debugging cycles for Docker builds
2. NPM Package Compatibility: Sharp module still problematic
3. Smaller Community: Limited Stack Overflow solutions
4. Learning Curve: Permission flags configuration overhead

Node.js Critical Issues

• None reported in 8-month production testing
• Predictable memory usage patterns
• Extensive debugging tools and community support

Resource Requirements

Implementation Time Investment

• Bun Migration: 2-3x estimated time due to compatibility issues
• Deno Migration: 1.5x estimated time due to permission system learning
• Node.js: Baseline time estimate reliable

Expertise Requirements

• Bun: Requires debugging Zig-level issues, limited community support
• Deno: Modern JavaScript knowledge, permission system understanding
• Node.js: Standard JavaScript expertise, extensive documentation

Operational Costs

• Bun: Higher debugging overhead, potential weekend outages
• Deno: Moderate learning curve, good documentation
• Node.js: Predictable maintenance costs, mature tooling

Decision Matrix by Use Case

High-Performance Requirements

Choose Bun if:

• Internal tooling where downtime acceptable
• Performance critical (>15k RPS requirements)
• Small team capable of exotic debugging
• Linux/Mac development environment only

Risk Assessment: High performance gain with high operational risk

Modern Development Experience

Choose Deno 2.0 if:

• TypeScript-first development required
• Security permissions model beneficial
• Starting new projects without legacy constraints
• Serverless/edge deployment target

Risk Assessment: Moderate performance gain with low operational risk

Enterprise/Critical Systems

Choose Node.js if:

• System availability critical (>99.9% uptime requirements)
• Large development team
• Enterprise support requirements
• Windows compatibility needed
• Extensive npm ecosystem dependencies

Risk Assessment: Standard performance with minimal operational risk

Migration Warnings

Package Compatibility Issues

High-Risk Packages:

• bcrypt: Native compilation issues with Bun
• sharp: Image processing failures in Deno
• Prisma: Segmentation faults in Bun Docker containers
• Native C++ modules: General compatibility problems

Platform-Specific Failures

Windows Development:

• Bun: File watching system completely broken
• Deno: Full compatibility
• Node.js: Full compatibility

Docker Deployment:

• Bun: Alpine Linux causes crashes, Ubuntu required
• Deno: Standard Docker patterns work
• Node.js: All base images compatible

Debugging Capabilities

Error Resolution Time

• Node.js: 10 minutes average (extensive Stack Overflow coverage)
• Deno: 30-60 minutes average (growing community)
• Bun: 2-6 hours average (cryptic Zig stack traces, limited community)

Monitoring Integration

• Node.js: Full APM integration (New Relic, DataDog, etc.)
• Deno: Basic monitoring available
• Bun: Limited production monitoring tools

Business Impact Assessment

Revenue Risk

• Bun: High risk - potential for extended outages during peak traffic
• Deno: Low risk - predictable performance characteristics
• Node.js: Minimal risk - mature operational patterns

Team Productivity Impact

• Bun: High initial productivity boost, potential for significant debugging overhead
• Deno: Moderate productivity improvement with modern tooling
• Node.js: Stable baseline productivity

Hiring Considerations

• Bun: Limited candidate pool familiar with runtime-specific issues
• Deno: Growing candidate pool, attractive to modern developers
• Node.js: Largest candidate pool, standard skill set

Recommended Implementation Strategy

New Projects

1. High Performance Requirements: Bun (with extensive testing)
2. Modern Tooling Priority: Deno 2.0
3. Enterprise Requirements: Node.js

Migration Projects

1. Performance Critical: Gradual Bun migration with rollback plan
2. Modernization Focus: Deno 2.0 for new services
3. Risk Averse: Remain with Node.js, optimize existing implementation

Team Size Considerations

• <5 developers: Bun acceptable risk level
• 5-20 developers: Deno 2.0 optimal balance
• >20 developers: Node.js operational safety required