Solopreneur Site Performance Revamp

My one-person business site has grown steadily, but the pages now hesitate before they show up, and that lag is costing conversions. The immediate goal is to tighten every layer of the build so visitors notice speed, not spinners... (Budget: $250 - $750 USD, Jobs: GTmetrix, HTML, JavaScript, PHP, Web Design, Web Development, Website Design, Website Optimization)