Where Web Design Trends Have Been

Latency is an often forgotten concern when it comes to website performance. There are ways to testing your current site for a variety of performance settings, including customising latency.

Recently I’ve been working on a talk for the MobX Conference in Berlin, Germany. The talk was originally going to be around building for performance and focussing on the approach to building responsible responsive websites. The reason is that I wanted to keep performance on the front of everyones minds and ensure that the traditional argument that responsive design sites are too slow for mobile could be debunked. While I ended up changing tact with the talk to be a more universal talk I still spent time looking at the issues of poor performance and how to overcome that.

The only way that you can truly overcome something is by having a good understanding of the problem at hand, and this in turn allows you track and test the challenges at every angle. When it came to responsive design and performance there were a few different areas I was looking at during the talk including preconnect, prefetch, prerender, critical CSS and latency (plus a few more that didn’t end up making the talk).

Latency is one area of web performance that never seems to get a lot of attention, perhaps because the simple fact of latency can not really be changed.

WHAT IS LATENCY?

Lets defer to the all knowing google/wikipedia...

Latency is a time interval between the stimulation and response, or, from a more general point of view, as a time delay between the cause and the effect of some physical change in the system being observed.

In web speak it is the round trip time between you requesting a http request and the returning answer. The longer the request takes to get an answer... the longer the latency. This has no bearing on whether you're requesting a 10kb HTML document or a 5MB image... we're talking about the time it takes from the start of the request until you get an answer. In the case of the HTML document and image request the latency will be the same for each of them (assuming they're on the same server) however the image download will take longer, however the download time is down to connection speed/bandwidth.

FRONT END PERFORMANCE TESTING TOOLS

I like to use a variety of testing tools when looking at the performance of sites, each testing tools is better at doing one thing or another and I like a good even spread of results to ensure you're taking everything into consideration.

In my work on the talk I was able to test and retest the results to show the improvement for preconnect, prefetch, prerender, and critical CSS but I wasn't really able to track down latency issues. The tools I use for testing include Dial up 56kb modem — 49/30 Kbps 120ms RTT (it would be awesome if they also broadcast the old modem dialup sounds with this too). The trouble I had was that I wanted to show the difference between a 5MB connection when it had 50ms of latency and a 10MB connection when it had 500ms of latency so that I could show a larger bandwidth is not necessarily faster if the latency is worse. source by:https://responsivedesign.is/articles/testing-for-latency