Performance issues rarely arrive without warnings. Watch blended signals instead of a single metric.
- Sustained CPU steal time on virtual instances.
- Growing p95/p99 latency while errors remain flat.
- Disk queue depth climbing during backups or batch jobs.
- Database connections hovering near pool limits.
- CDN cache hit ratio drifting down unexpectedly.
When two or more persist through a weekly window, plan capacity or isolate noisy neighbours before peak season.