MySQL Server Performance Optimization

We are facing serious performance issues with our live server running MySQL on a cPanel-based VPS. The site is frequently slow or unreachable, and our monitoring shows extremely high CPU usage (over 90% by mysqld) and heavy memory load (over 5.2 GB used out of 5.6 GB RAM, and 3.5 GB swap usage).

What We Need Help With:
Identify and fix the root cause of high CPU and RAM usage by MySQL

Analyze slow queries and optimize them

Adjust MySQL configuration for better performance (low-resource server)

Suggest and implement tweaks to reduce server load

Minimal downtime while fixing (live server)

Tech Stack & Environment:
CentOS / cPanel VPS

Apache + MySQL (InnoDB-heavy)

PHP (mostly WordPress and custom PHP)

Total RAM: 5.6 GB

CPU Cores: 4

Swap: 4 GB (mostly used)

cPanel, WHM access available

Ideal Freelancer:
Proven experience in MySQL query optimization and server performance tuning

Comfortable working with low-resource servers

Familiar with slow query logs, my.cnf tuning, and live troubleshooting

Affordable and quick turnaround (this is a low-budget, time-sensitive task)