Boost PageSpeed to 90+ Score

My single-page WordPress site was recently redesigned and now looks great, yet it still lags on Google PageSpeed Insights. I need every metric—Performance, Accessibility, Best Practices and SEO—to score 90 or above on both mobile and desktop... (Budget: ₹600 - ₹1500 INR, Jobs: Accessibility, CSS, Google PageSpeed Insights, HTML, PHP, SEO, Web Design, Web Development, Website Optimization, WordPress)