Minimize page startup cost

[paulirish]

The content script injection at document_start has some fairly sizable cost associated. 50ms on my modern MacBook Air.

To be fair, it appears the cost is actually all the extension subsystem. Nearly all cost is once chrome.runtime.connect({name: vAPI.sessionId}) is called.

Is there any opportunity to 1) avoid the content script injection or 2) avoid this runtime.connect call under certain circumstances?

[gorhill]

Is there any opportunity to 1) avoid the content script injection

The content scripts are injected declaratively through manifest.json. The only time I can think content scripts are not needed is when a site is whitelisted, otherwise the content scripts are needed to find out if and what cosmetic filtering needs to apply + whether the DOM counterpart of whatever blocked network request needs to be collapsed.

On my desktop i5 I get under 20 ms for vAPI.messaging.setup. My understanding from reading the API doc is that ports (chrome.runtime.connect) should be used whenever there is a chance for a lot of back-and-forth messaging.

[gorhill]

I stepped into Chrome API code, specifically Binding.generate, and I see forEach being used a lot (including forEach within forEach), and my understanding of forEach is that it is quite sub-optimal. I would be curious to see this code profiled against just using plain vanilla loops.

[gorhill]

Marking as browser bug: https://bugs.chromium.org/p/chromium/issues/detail?id=653596.