High Blocking Time In A Specific Store (Urgent)

Shopify Discussion
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Topic summary

A Shopify store using the Warehouse theme is experiencing severe performance issues with 82% performance score and 380ms Total Blocking Time (TBT) in GTmetrix testing.

Key Problem:

  • The same theme performs excellently (99% speed, 62ms TBT) in a clean test store
  • Performance degrades significantly when deployed to the specific production store
  • Issue persists despite uninstalling apps and disabling pages/categories

Current Status:

  • User has provided GTmetrix report links comparing the problematic store against a test environment
  • The production store has several modifications to structure and design, while the test store uses the original theme without customizations
  • Seeking urgent help to identify and resolve the blocking time issue

The problem appears isolated to this specific store environment rather than the theme itself, suggesting store-specific content, configurations, or remaining apps may be causing the performance degradation.

Summarized with AI on November 23. AI used: claude-sonnet-4-5-20250929.
1

Hello friends, I need some help here.
I have a store with the Warehouse theme, but it is giving 82% performance and 380ms of TBT (total blocking time) in GTmetrix. In another test store, with nothing and with the same theme, it gave only 62ms of TBT and 99% speed along with 99% structure and other very low data.

Can you help me? I’ve tried uninstalling some apps, pages I disabled from the site, categories etc, but it didn’t download the TBT.

Note: I tested the same theme in another store and it gave a speed of 99%, but when I put the theme in that specific store and I already test it in GTmetrix it only gives 82% speed and this very high TBT.
I don’t know how to solve it myself, I hope someone can help me to detect the problem, I will be very happy.

Complementing the question, I have the same theme (Warehouse) but with several modifications made to its structure and design, and it does not have this gigantic blocking time testing in the same store where the original theme and without modifications has a large TBT.

My store:

https://kingstorebrasil.com.br

My store’s GTmetrix result:
https://gtmetrix.com/reports/kingstorebrasil.com.br/1WYV8WTP/

GTmetrix from a test store:
https://gtmetrix.com/reports/kingstorebrasilecom.myshopify.com/RCk6fern/