TBT (Total Blocking Time) too high
The Total Blocking Time (TBT) is too high. Long JavaScript tasks block the main thread and prevent the page from responding to interactions.
Why it matters
A high TBT makes the page non-interactive during loading. The user clicks but nothing happens, generating frustration and abandonment.
How to fix
- 1
Identify long tasks
Chrome DevTools → Performance → record the load → "Main Thread" section → look for red "Long Task" blocks (> 50ms). These are your culprits.
- 2
Defer non-critical JavaScript
html<!-- Add defer or async to scripts --> <script src="analytics.js" defer></script> <script src="chat-widget.js" async></script> - 3
Reduce or remove third-party scripts
Each third-party widget (chat, analytics, advertising) adds JavaScript. Evaluate the real impact of each and remove the least used ones.
- 4
Via WP Rocket: JS optimization
WP Rocket → File Optimization → "Load deferred JS" → "Delay JS execution". Warning: test carefully as this may break some plugins.
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