Diagnose Memory Leak

Diagnose and fix a memory leak:

Environment: {{ENVIRONMENT}}
Symptoms: {{SYMPTOMS}}

Investigation approach:
1. Take heap snapshots before and after suspected leak
2. Compare snapshots to find growing objects
3. Check for common patterns:
   - Event listeners not removed
   - Closures holding references
   - Global variables accumulating data
   - Timer intervals not cleared
   - Unclosed database connections
   - Cache without eviction
4. Identify the root cause
5. Implement fix
6. Verify fix with heap snapshot comparison

Provide:
- Memory profiling instructions
- Code changes to fix the leak
- Test to verify fix
- Prevention patterns for future code