How can I diagnose and measure performance issues in cPanel hosting environments?

In a shared or VPS cPanel hosting environment, I need to pinpoint the root cause of intermittent slow page loads and high CPU usage. The server hosts multiple websites, each with its own resource limits, and the cPanel interface does not provide granular real‑time metrics. I want to capture detailed performance data, correlate it with user traffic patterns, and then apply targeted optimizations. The constraints include limited access to low‑level system tools, the need to avoid service interruptions, and uncertainty about which cPanel‑specific modules may influence resource consumption. I am looking for a systematic approach to collect, analyze, and interpret performance measurements.

Specifically:

• What are the recommended methods to gather reliable CPU, memory, and I/O statistics on a cPanel server?
• How can I correlate these metrics with cPanel’s own resource‑limiting features (e.g., CPU, memory, and bandwidth limits)?
• Which tools or scripts are compatible with cPanel that can automate data collection and flag potential bottlenecks?