Sentinel: Your Web-Performance Watchman

Web Performance Consultancy

Web performance impacts all businesses. How does it affect yours?

I work together with organisations of all sizes to analyse, find, and fix site-speed issues. How much does a one-second slowdown affect conversion rates? Are third party scripts impacting engagement? How does site-speed influence revenues?

It’s my job to help you find out.

Consulting with the team at 13|37.

Consultancy engagements are tailored to each client and project, but they all combine some or all of the following:

  • Analysis: You can’t fix what you can’t measure. Let’s work out just how site-speed affects your business. Once we have an idea of exactly what web performance means for you, we’re far better equipped to make meaningful improvements.
  • Audits: I’m a technical consultant at heart—I have a forensic knowledge of how both the network and web browsers work. My audits are famed for their extensive, detailed, yet actionable insights, and will uncover everything that is working against us.
  • Implementation: Performance sprints are a highly effective way to realise returns fast. I’ll work alongside your engineering team to get customer-facing site-speed improvements out of the door and earning you money. I won’t just find the problems—I’ll fix them.
  • Culture: You should never need to call pest control twice. I will ensure your team is left self-sufficient and able to tackle these issues themselves in future. Let’s build a performance culture that bakes site-speed considerations into projects from the outset. Let’s make it easy to do the right thing.

I pride myself on my ability to work with organisations and not merely for them. So much so that I wrote a book about it.

Let’s Talk!


For lighter-touch guidance and advice, we can schedule 90-minute consultations to answer your most pressing questions: want to work out what a slow website is costing your business? Need to know where you should focus your efforts first? Looking for help troubleshooting specific performance issues? Let’s get your answers.

Consultations are a great idea if:

  1. you have a specific, distinct issue that you don’t need a weeks-long consultancy project to solve;
  2. you want to start your site-speed journey more tentatively, testing the water with a smaller commitment at the beginning.

If we go on to work together more fully after our initial consultation, it gets discounted from your first consultancy invoice. Win-win, no risk!

Schedule a Consultation

A consultation is not just a call—when you schedule a consultation, I’ll ask you to provide me with any relevant research, homework, and tasks so that I can fully prepare for our meeting. Want me to look over some waterfall charts? You got it! Need me to debug some stuff? Send me a URL. Need a second opinion on your Vitals? I’m on it!

Got Questions?

How much will it cost?

You’d be surprised. From $1,000 to $100,000, there’s always something we’ll be able to do to help solve your problem. My approach is to design the engagement around you, so your best option is to get in touch and let me work something out.

Do you work with smaller organisations?

Absolutely! While my client list tends to highlight more familiar household names, I love partnering with anyone who’s keen to do good work. In fact, some of my most fond memories are joining smaller teams and working closely together to solve problems.

Whether it’s consultancy, audits, or training, the size of your company does not matter. There’s something for everyone.

How long will it take?

Probably not as long as you think! Over the past six years, I have managed to optimise my workflow to such an extent that we can move incredibly quickly. Vitamix had this to say about it:

Harry’s technique for getting to the root of our needs was phenomenal—he proposed a tailor made plan of action, and it was spot on. We were able to implement it immediately and it didn’t take weeks or months of ramp-up time. It was as if Harry had been in the trenches with us all along!

No matter how long it will take us to achieve our goals, the sooner we start, the better.

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.

You can now find me on Mastodon.

Suffering? Fix It Fast!


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Next Appearance

  • Talk & Workshop

    WebExpo: Prague (Czech Republic), May 2024


I am available for hire to consult, advise, and develop with passionate product teams across the globe.

I specialise in large, product-based projects where performance, scalability, and maintainability are paramount.