Getting started with render-blocking resources
We end up explaining this on discovery calls often enough that it deserved writing down. A short on-ramp to render-blocking resources for teams who have not touched it before.
Real-world numbers from actual visitors matter more than a score produced on a fast laptop. If it only works because one person remembers to do something, it does not work yet.
What is actually at stake
Scripts and styles in the head delay the first paint. The reasoning matters more than the rule, because the rule has exceptions. The version that survives contact with a real deadline is the simple one.
Your first week
- Find out what is already in place
- Defer anything that is not needed immediately
- Change one thing and measure it
Third-party tags are frequent offenders. Where this goes wrong is almost never a lack of knowledge. It rarely shows up as a line item, which is exactly why it slips.
How to tell if yours is fine
Performance work is mostly subtraction, which makes it unpopular and effective. Three things worth confirming about render-blocking resources before you move on:
- Someone can say what the current setup is without going to look
- Third-party tags are frequent offenders — and you know whether that is true here
- There is a way to tell whether the last change to this helped
If any of that sounds like a description of your current setup, it is fixable.