Performance at Scale with Ryan Townsend (Cloudflare) | Black Friday, Edge Caching, Cache Hit Ratios

You can't optimize what you don't measure. So why do so many teams still guess?

In this episode of Señors at Scale, I sit down with Ryan Townsend, Principal Product Manager for Performance at Cloudflare. Ryan has spent 20+ years building for the web and a decade as a CTO. He co-founded Shift Commerce, an enterprise-scale headless SaaS e-commerce platform built on Ruby on Rails that handled billions in yearly revenue. Before that, he was CTO of Matalan Direct, which grew out of one of Shopify's fastest-growing businesses.

We talk about why "Rails doesn't scale" was always a myth and how learning Rails in 2005 felt like AI feels today. Ryan also explains how he learned to let go of the code as a leader, using guardrails, weekly demos, and T-shaped engineers.

Then we get deep into performance: why real user data beats Lighthouse on your MacBook, how one "no performance impact" personalization script cost seconds at P90, and how Shift hit 99%+ cache hit ratios using inventory tiers and edge personalization.

Key Topics:

- Why "Rails doesn't scale" was always a myth

- Resume-driven development and why startups over-hire CTOs

- Why deep experience plus AI is a superpower, and the junior talent pipeline problem

- Letting go of the code: guardrails, weekly demos, and async leadership

- T-shaped engineers and spreading context across teams

- Adopting Scrum properly, training with Jeff Sutherland, and removing impediments

- Cutting CI from 40 minutes to 3

- Real user monitoring vs synthetic testing

- The render-blocking personalization script that cost seconds at P90

- 99%+ cache hit ratios, inventory tiers, and personalizing cached pages at the edge

- Preparing for Black Friday traffic spikes

CONNECT WITH RYAN

💼 LinkedIn: https://www.linkedin.com/in/ryantownsend/

🦋 Bluesky: https://bsky.app/profile/twnsnd.com

🐙 GitHub: https://github.com/ryantownsend

🌐 Website: https://twnsnd.com

FOLLOW & SUBSCRIBE

🎙️ Podcast: https://neciudan.dev/senors-at-scale

📬 Newsletter: https://neciudan.dev/subscribe

💼 Dan's LinkedIn: https://www.linkedin.com/in/neciudan

💼 Señors at Scale LinkedIn: https://www.linkedin.com/company/senors-scale/

📸 Señors at Scale Instagram: https://www.instagram.com/senorsatscale/

📸 Dan's Instagram: https://www.instagram.com/neciudev

ADDITIONAL RESOURCES

📘 The Phoenix Project by Gene Kim, Kevin Behr, and George Spafford

⚡ Cloudflare Speed docs: https://developers.cloudflare.com/speed/

🐢 Ryan's slowest site in the world (web perf practice repo): https://github.com/ryantownsend/slowest-site-in-the-world

#WebPerformance #Cloudflare #RubyOnRails #Ecommerce #CoreWebVitals #EngineeringLeadership #SeniorsAtScale

💬 What's the biggest performance win you've found by actually measuring instead of guessing?