Fastly CDN: AI-Optimized Technical Reference

Executive Summary

Fastly is a premium CDN with 3x higher costs than competitors, delivering 12ms API responses that remain stable during 45x traffic spikes. Worth the premium only for revenue-critical applications in North America/Europe where latency directly impacts business metrics.

Performance Specifications

Latency Benchmarks (8-month production data)

Region	Fastly	Cloudflare	AWS CloudFront	Critical Impact
North America	12-18ms	15-22ms	25-35ms	Fastly wins marginally
Europe	18-24ms	16-20ms	28-40ms	Cloudflare superior
Asia-Pacific	80-120ms	20-35ms	45-60ms	FAILURE: Fastly unusable

Cache Performance

• Cache purge speed: 150ms globally (vs 15+ minutes AWS CloudFront)
• Traffic spike stability: No latency degradation during 45x traffic increases
• Uptime: 99.95% (vs Cloudflare 99.98%, AWS 99.96%)

Critical Failure Scenarios

Geographic Coverage Failures

• Asia-Pacific coverage: Only 3 POPs for entire region
• Impact: 80-120ms latencies make apps unusable for Asian users
• Consequence: User abandonment in Southeast Asia markets

Billing Shock Events

• Traffic spike costs: $400/month → $3,200/month during events
• Hidden charges: Request fees ($0.0075/10K) on top of bandwidth
• Break-even threshold: Need $12,000+/month revenue impact to justify costs

Single Point of Failure Risk

• June 2021 outage: 58 minutes global downtime
• Revenue impact: $47,000 lost during single hour
• Affected services: Reddit, GitHub, CNN, Twitch simultaneously

Cost Analysis

Real Production Costs (8-month tracking)

• Month 1 (testing): $127
• Month 3 (production): $847
• Month 6 (traffic spike): $3,247
• Month 8 (steady state): $672
• Total investment: $12,000 over 8 months

Cost Comparison (5TB/month)

• Fastly: $672/month average ($3,200 during spikes)
• Cloudflare: $25/month (until fair use limits)
• AWS CloudFront: $180/month

ROI Threshold

• Conversion improvement: 3.2% → 3.8% (+0.6%)
• Revenue impact: $12,000/month additional on $200k volume
• Break-even: Premium justified only above $200k/month transaction volume

Implementation Requirements

Technical Prerequisites

• Learning curve: 40+ hours for VCL configuration mastery
• WebAssembly expertise: Required for edge computing features
• Debugging complexity: Distributed system troubleshooting skills
• Migration effort: 2+ weeks for proper setup/migration

Infrastructure Dependencies

• Vendor lock-in: VCL configuration non-portable
• Multi-CDN strategy: Required for production resilience
• Monitoring requirements: Real-time analytics essential for cost control

Decision Matrix

Use Fastly When:

• Revenue directly correlates with latency (sub-50ms requirement)
• Users primarily in North America/Europe (>80% traffic)
• Enterprise budget available ($500+/month CDN acceptable)
• Complex edge computing needs beyond simple redirects
• Traffic spike resilience critical (Black Friday, viral events)

Avoid Fastly When:

• Startup/budget constraints (<$200k/month revenue)
• Global user base (especially Asia-Pacific focus)
• Static content serving (blogs, marketing sites)
• No direct latency-revenue correlation measurable

Application-Specific Recommendations

Application Type	Fastly Rating	Better Alternative	Justification
Fintech/Trading	Mandatory	None	Every millisecond impacts trading revenue
Gaming (competitive)	Recommended	None	Player retention depends on consistent latency
E-commerce (high-traffic)	Conditional	Cloudflare Pro	Only if conversion rates measurably improve
SaaS API-heavy	Conditional	Cloudflare Pro	Depends on API performance impact on UX
Content/Media	Not recommended	Cloudflare Free	Basic CDN sufficient
Startup MVP	Avoid	Cloudflare Free	Spend budget on development instead
Global B2C (Asia focus)	Avoid	Cloudflare/AWS	Fastly's Asian coverage inadequate

Configuration Warnings

Production Gotchas

• Default settings fail under load - requires custom VCL tuning
• Request charges unexpected - can double bandwidth costs
• Edge function cold starts add 15-25ms latency on first requests
• Documentation quality poor for advanced configurations

Critical Monitoring Points

• Asia-Pacific response times - early indicator of geographic issues
• Cost per GB trends - spike warnings for traffic events
• Cache hit ratios - optimization opportunities
• Error rates during traffic spikes - capacity planning needs

Edge Computing Capabilities

WebAssembly Performance

• 200ms page load improvement for personalization logic
• 40% origin server load reduction for geo-location/A/B testing
• Cold start penalty: 15-25ms on first requests
• Debugging complexity: High - distributed WebAssembly troubleshooting

Limitations

• Not suitable for complex business logic
• Limited runtime environment compared to full serverless
• Debugging tools immature for production issues

Support Quality Assessment

Enterprise Support

• Response time: 10 minutes for critical issues
• Technical expertise: WebAssembly debugging capability
• Availability: 24/7 with human engineers

Basic Support

• Quality: Chatbot-first, limited technical depth
• Escalation required: For any complex configuration issues

Risk Mitigation Strategies

Redundancy Requirements

• Multi-CDN architecture: Essential for mission-critical apps
• Failover automation: Required due to 99.95% uptime SLA
• Cost monitoring: Real-time alerts for billing spikes

Migration Preparedness

• VCL configuration backup: Non-portable, plan for rewrite
• DNS switching capability: For emergency failover
• Performance baseline tracking: For comparison during migrations

Resource Requirements

Human Resources

• Senior DevOps engineer: 2-4 weeks initial setup
• Ongoing maintenance: 4-8 hours/month for optimization
• Incident response: 24/7 on-call capability for outages

Financial Planning

• Minimum budget: $500/month for meaningful usage
• Spike reserves: 5-10x normal costs for viral events
• Migration buffer: $10,000+ engineering time for vendor change