Should developers worry about Idle time?

[Garbee]

An often question that comes up is, "What is Idle time?" and "How do I get rid of it?".

This recently hit the ML again. These questions should be answered in the docs directly.

We should answer:

• Do you need to worry about Idle time?
• What are some examples of things that cause Idle time?
• Do you need to worry about un-instrumented time?
• Any known examples of what can't be instrumented currently?

[paulirish]

Idle doesnt belong in the pie chart or any % calculations. That's a bug, IMO.

Idle time has different concerns but they're very unrelated to how we currently present it.