Achieve 90+ PageSpeed Score -- 2

I need a focused optimisation pass that lifts my Shopify site’s Google PageSpeed Insights scores—loading speed, cumulative layout shift, and overall performance—to 90 or higher on both mobile and desktop.

Here’s what I expect you to tackle:
• Identify the heaviest scripts, stylesheets, images, or third-party snippets (there are only a few apps in use) and either streamline, defer, or lazy-load them.
• Eliminate cumulative layout shift by reserving space for ads, images, and embeds.
• Apply lightweight best-practice tweaks—compression, minification, and sensible caching headers—without touching the existing theme structure or forcing a complete rebuild.

Deliverables
1. Before-and-after PageSpeed screenshots for mobile and desktop.
2. A concise changelog naming every file or setting you modified.
3. Verified 90+ scores for all three metrics on the live site.

You’ll work with the current codebase as-is; I can grant temporary access or accept patch files, whichever suits your workflow. Once complete, the improved scores must be visible on the public URL, not just in a staging environment.