How can I improve the loading speed of my vivid theme site?

Topic summary

Slow loading on a Vivid theme store, especially on mobile, with audits showing high LCP (Largest Contentful Paint: time to render the main content) and TBT (Total Blocking Time: time the main thread is blocked by scripts). Screenshots indicate low scores and heavy third‑party app impact.

Key causes identified:

  • Unused/legacy third‑party app code increasing request count and size.
  • Large images and suboptimal lazy loading affecting LCP.
  • Heavy JavaScript, long main‑thread tasks, and unused CSS/JS.

Recommended actions (from replies):

  • Remove unused app code; limit third‑party JS and apps.
  • Compress/resize images; defer off‑screen images; implement proper lazy loading (lazyload + data-src) and consider Critical CSS.
  • Reduce JS payload; code split; minimize main‑thread work; clean unused CSS/JS; migrate trackers to Google Tag Manager.
  • Optimize fonts (system fonts or preload; use font-display: swap). Consider a theme upgrade.

Latest update: After applying suggestions, some functionality broke; the requester asked for practical, step‑by‑step guidance. Another participant suggested video tutorials or hiring a speed optimization expert. No resolution yet; screenshots/audit images are central to understanding the issues.

Summarized with AI on January 4. AI used: gpt-5.

@oscprofessional

I trying best but ye not get any more change.
please explain the in details.

Because I am a new in this field.

Best,
Sohan