Why is my Dawn 13.0 theme causing slow store speed?

Topic summary

After updating to Dawn 13.0, the store’s speed dropped, with Google reporting CLS 0.21 (Cumulative Layout Shift: visual instability; lower than 0.1 is typically good). Unused apps were removed, but performance issues persist.

External checks show mobile PageSpeed ~53, while desktop performance is now acceptable. The main culprits cited: heavy images/videos, third‑party scripts (including leftovers after app removal), render‑blocking resources, and unused/minified CSS/JS, plus webfont loading and missing explicit image dimensions.

Suggested actions:

  • Audit and remove leftover third‑party scripts; minimize installed apps.
  • Optimize images (prefer WebP), properly size, set width/height, and defer offscreen images.
  • Minify and reduce unused CSS/JS; ensure text remains visible during webfont load.
  • Monitor key metrics: LCP (Largest Contentful Paint) and TTFB (Time to First Byte). Use PageSpeed Insights and WebPageTest for country‑level checks.

One view: if mobile TTFB is under 1s (especially within target regions), urgency is lower. Another view: performance tuning on Shopify is complex and may require a developer.

Status: partially improved (desktop), mobile remains slow. No final resolution; hiring an expert was recommended.

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

Thank you so much for your help! Is there a dummy proof way of improving your speed? I now a bit about coding and such but when i try to find the codes of apps in my theme code, i cant seem to find much…

Is there an easier way?