Magento Speed Stabilization Needed

My Magento storefront is experiencing noticeable performance swings—pages can feel snappy one moment and sluggish the next. The shop runs on a VPS, and the cause could lie in either the server configuration or the codebase; I have not pinpointed it yet... (Budget: ₹400 - ₹750 INR, Jobs: Apache, Linux, Magento, MySQL, Redis, Troubleshooting, VPS, Website Optimization)