Web Performance Optimisation, Consultancy, and Engineering

Trusted by:

Harry gave the team a strong footing for identifying performance issues on iPlayer. With his knowledge, we were able to roll out quick fixes to our audiences without the need for big rewrites, all within just two days.
Matthew Burrows, BBC iPlayer
Harry helped our team level up their scalable CSS architecture skills, and to say that he had a large impact on our work is an understatement. We can’t recommend him enough.
Addy Osmani, Google
Harry’s workshop was excellent; we left with tons of new ideas and techniques to improve both the CSS architecture and overall performance of Behance and Adobe Portfolio.
Jackie Balzer, Adobe
There’s a short list of people I whole-heartedly recommend for detailed performance work; Harry is right up there at the top.
Tim Kadlec
The CSS architecture I learned from Harry on the NHS project has changed the way I work. Bravo!
Josh Nesbitt

Web Performance and Site-Speed Insights

There are 237 articles on this blog. Find them all on the blog page.

18 August, 2025
Low- and Mid-Tier Mobile for the Real World (2025)
27 July, 2025
The Fastest Site in the Tour de France
25 July, 2025
Making Sense of the Performance Extensibility API
7 March, 2025
Why Do We Have a Cache-Control Request Header?
10 February, 2025
HTML Is Not a Programming Language…
23 January, 2025
Build for the Web, Build on the Web, Build with the Web
4 December, 2024
Licensing Code on CSS Wizardry
2 December, 2024
A Layered Approach to Speculation Rules
26 November, 2024
Designing (and Evolving) a New Web Performance Score
18 November, 2024
Core Web Vitals Colours

Older articles

Hi there, I’m Harry Roberts. I am an award-winning Consultant Web Performance Engineer, designer, developer, writer, and speaker from the UK. I write, Tweet, speak, and share code about measuring and improving site-speed. You should hire me.

Connect

Projects

ITCSS – coming soon…

Next Appearance

Talk
ANWB Front-End Summit: The Hague (Netherlands), June 2025

Learn:

I help teams achieve class-leading web performance, providing consultancy, guidance, and hands-on expertise.

I specialise in tackling complex, large-scale projects where speed, scalability, and reliability are critical to success.

Start a Conversation

Audits

Consultancy

Training