WordPress Speed Optimization & Upgrade

My goal is simple: make www.pianoiris.com feel instantly responsive without changing its familiar look. The site currently sits on WordPress 6.2.10 with PHP 5.6.40 and an abandoned theme, so the first step will be to refactor that theme so it runs safely on the latest WordPress core and PHP 8.x while preserving every layout element visitors already know.

Once compatibility is secured, I need you to:
• Track down the specific bottlenecks that slow down page-load time and hurt server response, especially on the homepage and key product/service pages.
• Implement proven fixes—code clean-up, database queries, image and media compression, caching (object and browser), minification, and CDN configuration if useful.
• Deliver a fully upgraded WordPress installation, theme, and plugin set that scores noticeably higher on Lighthouse, GTmetrix or PageSpeed Insights.

I’ll consider the job complete when the upgraded site retains its current design yet loads significantly faster across desktop and mobile, with measurable gains in the above tools and no functionality broken. Tell me how you plan to tackle the theme update, the diagnostics you’ll run, and the optimisation stack you prefer so I can move forward quickly.