Main Thread
The main thread is the primary "workspace" within a web browser where it performs most of the work required to display a webpage. This includes parsing HTML and CSS, executing JavaScript, and responding to user interactions. If the main thread is busy for too long with a heavy script, it becomes "blocked" and cannot respond to user clicks or taps, leading to a laggy, unresponsive experience and a poor Interaction to Next Paint (INP) score.
Related web performance terms
- Machine Learning Models
These are the algorithms that power Speed Kit's Prediction Engine. They are trained on billions of anonymous user interactions collected from our Real User Monitoring (RUM) system to identify patte…
- Metadata Management (Image)
This is part of Speed Kit's Image Optimization process. It involves automatically stripping non-essential, invisible data (metadata) from image files.
- Multi-Page Application (MPA)
A Multi-Page Application is a traditional website architecture where each distinct page is a separate HTML document. Every navigation from one page to another involves a full page reload (Hard Navi…
- A/B Testing
A/B testing is a method of comparing two versions of a webpage to see which one performs better. For example, an e-commerce store might show 50% of its visitors a green "Buy Now" button (Version A)…