Andy Davies

Adding Public Locations to a Private WebPageTest Instance

If you’ve got your own Private WebPageTest instance, and you want to add extra locations without setting up the test agents yourself then you can add agents from another instance.

Once configured your local WebPageTest instance submits tests and retrieves results via the API of the remote WebPageTest instance (aka Relay Server), and the pages are tested on the remote instance’s agents.

Using a Relay Server is also handy if you want to do local development on the server code without needing to setup Windows (or mobile) test agents.

Accelerated Mobile Pages - I’ve Got More Questions Than Answers

So Google, a group of publishers and others have launched Accelerated Mobile Pages (AMP)

AMP promotes the goal of a faster mobile web which is something I think we’d all like to see.

If you visit on a mobile, and search for ‘Obama’ there’s no doubt the stories in the carousel come up fast, and moving between them is slick too. The demo isn’t available in all regions yet so Addy Osmani posted a demo to YouTube.

Similar to Google’s Instant Pages, AMP relies on pre-rendering and caching to make the pages load instantly.

How the Browser Pre-loader Makes Pages Load Faster

The pre-loader (also known as the speculative or look-ahead pre-parser) may be the single biggest improvement ever made to browser performance.

During their implementation Mozilla reported a 19% improvement in load times, and in a test against the Alexa top 2,000 sites Google found around a 20% improvement.

It’s not a new browser feature but some seem to believe it’s Chrome only and yet others suggest it’s “the most destructive ‘performance enhancement’ there’s ever been”!

So what is the pre-loader and how does it improve performance?

Using a Private Instance of the HTTP Archive to Explore Site Performance

With our current tools it’s relatively easy to examine the performance of a single page, or the performance of a journey a visitor takes through a series of pages but when I examine a client’s site for the first time I often want to get a broad view of performance across the whole site.

There are a few tools that can crawl a site and produce performance reports, from Peter Hedenskog and NCC Group’s (was Site Confidence) Performance Analyser are two I use regularly.

Sometimes I want more than these tools offer - I might want to test from the USA or Japan, or want some measurements they don’t provide - that’s when I use my own instance of the HTTP Archive.

Creating Page Load Waterfalls for Older Mobile Devices

Like most people involved in web performance I spend hours looking at page load waterfalls, each one tells it’s own story and the patterns hint at where the issues are.

With tools like Mobitest, WebPageTest, remote debugging in Chrome and Safari I can get a good level of detail for modern mobile browsers but I often want to test on older devices where the dev tools support isn’t as good or more commonly non-existent.

A proxy like Charles is one way of generating HARs from old devices but using a proxy can alter the waterfall so I prefer to generate waterwalls from a TCP packet capture.