Claude Code Performance Degradation: A Session Management Hypothesis
This technical assessment analyzes persistent Claude Code performance issues affecting coding capabilities and instruction following. Evidence suggests these stem from a critical session lifecycle management bug in Anthropic's backend infrastructure where authentication sessions accumulate due to failed cleanup processes, causing "sticky routing" to degraded servers.
Executive Summary
Key Finding
The account-specific nature of these issues, combined with their persistence across clean installations and new environments, points to backend session management failures rather than client-side problems or model degradation.
Problem Statement
Recent persistent performance issues with Claude Code, particularly affecting coding capabilities and instruction following, may stem from a critical session lifecycle management bug in Anthropic's backend infrastructure. This hypothesis suggests that authentication sessions accumulate on user accounts due to failed cleanup processes, causing "sticky routing" to degraded servers that persists even across fresh installations and new environments.
Impact
- User Experience: Claude Code becomes "essentially useless" for affected users
- Persistence: Issues continue across fresh VM installations and new environments
- Business Impact: Forced subscription cancellations and reduced user confidence
- Mixed Impact: Some users unaffected while others severely impacted
Technical Background
Claude Code Architecture
Claude Code operates as an NPM-distributed CLI tool that requires OAuth authentication with Anthropic's backend services. The architecture involves:
NPM Installation
Global installation via npm install -g @anthropic-ai/claude-code
OAuth Authentication
Initial setup triggers browser-based OAuth flow through localhost:54545 callback
Session Management
Persistent sessions maintained for context, file tracking, and environment state
Backend Routing
User requests routed to appropriate server clusters based on session data
Authentication Flow
# Installation
npm install -g @anthropic-ai/claude-code
# First run triggers OAuth
claude
# Opens browser for authentication
# Generates tokens stored in ~/.claude/.credentials.jsonOAuth Process Steps:
- Authorization Request: Client requests access with PKCE challenge
- User Authentication: Browser-based login and permission grant
- Token Exchange: Authorization code exchanged for access/refresh tokens
- Session Creation: Backend creates session record linked to user account
- Routing Assignment: Session associated with server cluster for load balancing
Session Persistence Requirements
Claude Code requires stateful sessions to maintain:
- Conversation context across terminal interactions
- File system state and modifications
- Environment configurations and permissions
- Background processes and shell state
- Project-specific settings and workflows
Core Hypothesis: Session Buildup Bug
The Theory
The performance degradation stems from a session lifecycle management bug where:
Session Creation
Each Claude Code authentication creates a backend session record
Failed Cleanup
When users revoke sessions or uninstall, backend cleanup processes fail
Session Accumulation
Orphaned sessions accumulate in user account records
Sticky Routing
Load balancers continue routing based on stale session data
Degraded Experience
Users consistently routed to problematic server clusters
Technical Mechanism
Normal Flow:
Create Session → Authenticate → Use → Expire/Revoke → [CLEANUP] → Remove from Routing
Bug Flow:
Create Session → Authenticate → Use → Expire/Revoke → [CLEANUP FAILS] → Routing Persists
Why This Explains the Symptoms
Fresh installations don't fix issues
Account-level routing corruption persists regardless of client environment
Mixed user experiences
Some users experience severe dysfunction while others work normally
Problems worsen over time
Accumulated sessions cause progressive degradation
Cross-environment persistence
Issues persist across different environments, VMs, and cloud platforms
Supporting Evidence
Evidence from Anthropic's Postmortem
"Context Window Routing Error: Certain user requests meant for Sonnet 4 were misrouted to servers anticipating a 1 million token context window. This misrouting initially affected a small percentage but peaked at 16%, degrading responses and causing 'sticky' behavior where affected users repeatedly hit wrong servers."— Anthropic Official Postmortem, September 16, 2025
This directly supports the session buildup hypothesis - users getting "stuck" hitting degraded servers due to routing issues.
User-Reported Patterns
Persistence Across Environments
- "Claude Code had become essentially useless for me, even in fresh NPM installs in brand new environments on newly rented VMs"
- Issues persist on HuggingFace Spaces and GitHub Codespaces
- Clean installations fail to resolve problems
Account-Specific Impact
- Mixed user experiences - some report normal operation while others face severe issues
- Problems tied to specific accounts rather than general service degradation
- Users forced to cancel subscriptions due to persistent issues
Progressive Degradation
- Claude Code "measurably losing the ability to perform basic coding"
- Gradual worsening over time rather than sudden failures
- Refusal to read CLAUDE.md or follow basic instructions
- Increasing use of placeholder code instead of functional implementations
Technical Evidence from Community Reports
GitHub Issues
- Session-destroying failures from compaction timeouts (#2423)
- Account token persistence across different credentials (#5931)
- Session termination causing complete context loss (#4165)
- Session contamination and incorrect context persistence
Authentication Problems
- OAuth expired errors without triggering new auth flows
- Interactive login broken while direct token setup works
- Authentication state conflicts between different accounts
Technical Analysis
Session Lifecycle Failure Points
Race Conditions in Cleanup
User Action: Revoke Session
Backend Process 1: Mark session inactive
Backend Process 2: Remove from routing table
Backend Process 3: Delete session record
# If Process 2 or 3 fails, session remains in routingDatabase Transaction Failures
- Session deletion transactions may timeout or fail silently
- Partial cleanup leaves sessions in inconsistent states
- Concurrent operations during installation/removal create conflicts
Load Balancer Persistence
- Session affinity rules not updated when sessions are revoked
- Stale routing entries direct users to degraded server clusters
- Health checks may not detect session-level routing problems
Resource Exhaustion Symptoms
Accumulated sessions could cause:
Connection Pool Exhaustion
Too many stale sessions consuming connections
Rate Limiting Triggers
Account appearing to have excessive active sessions
Memory Leaks
Session management services retaining orphaned session data
Load Balancer Overload
Routing tables growing beyond optimal size
Infrastructure Scaling Issues
During Anthropic's rapid scaling, bugs likely introduced in:
- Session garbage collection processes
- Load balancer configuration updates
- Database migrations affecting session storage
- Caching layer inconsistencies between services
Impact Assessment
User Experience Impact
Account-Specific Degradation
- Performance issues tied to user accounts, not client environments
- Standard troubleshooting (reinstallation, new environments) ineffective
- Creates appearance of user error rather than systematic bug
Business Impact
- Subscription cancellations due to unusable service
- Reduced confidence in Claude Code reliability for professional development
- Negative community feedback affects adoption and retention
Developer Workflow Disruption
- Inability to rely on Claude Code for consistent coding assistance
- Time wasted on ineffective troubleshooting attempts
- Forced migration to alternative tools and workflows
Technical Debt
Infrastructure Scaling Issues
- Session management becomes bottleneck for user growth
- Accumulated technical debt in session lifecycle processes
- Monitoring gaps prevent early detection of session health issues
Why This Bug Persists
Silent Failures
Session cleanup often runs as asynchronous background processes that may fail silently without user-visible errors or proper monitoring alerts.
Distributed System Complexity
Session state scattered across multiple services (auth, routing, app servers) with eventual consistency issues and network partition recovery problems.
Load-Dependent Manifestation
Bug may only manifest under specific load conditions or certain account activity patterns, making it difficult to reproduce and debug consistently.
Recommendations
Immediate Actions
Account-Level Session Cleanup
# Administrative tool to force session cleanup
admin-tool cleanup-user-sessions --account-id <user-id> --forceUser-Accessible Session Reset
# New CLI command for users to force session refresh
claude --reset-sessions --confirmEnhanced Diagnostics
# Session health diagnostic tool
claude --diagnose-sessionsSystemic Improvements
Session Lifecycle Monitoring
- Implement comprehensive session creation/deletion tracking
- Add alerting for session cleanup failures
- Monitor session accumulation rates per account
Routing Table Health
- Automatic routing table cleanup and validation
- Circuit breakers for degraded server routing
- Health checks that include session-level routing verification
Database Consistency
- Transaction logging for session operations
- Automated consistency checks and repair processes
- Improved error handling and retry logic for cleanup operations
Load Balancer Enhancements
- Dynamic routing table updates when sessions change
- Session affinity timeout and cleanup mechanisms
- Better integration between authentication and routing services
Long-term Architecture
Session Management Service
- Dedicated microservice for session lifecycle management
- Centralized session state with strong consistency guarantees
- Event-driven cleanup processes with guaranteed delivery
Monitoring and Observability
- Real-time session health dashboards
- Per-account session metrics and alerting
- Distributed tracing for session lifecycle operations
Testing and Validation
- Automated testing of session cleanup processes
- Load testing that includes session churn scenarios
- Chaos engineering for session management failure modes
Conclusion
The persistent, account-specific nature of Claude Code performance issues strongly suggests a backend session management bug rather than model degradation or general service issues. The hypothesis that failed session cleanup causes sticky routing to degraded servers explains the key symptoms and provides a clear path toward resolution.