# Simon Hearne

> Simon Hearne helps teams build fast search over unstructured data: vector databases, RAG pipelines, and over a decade of web performance craft.

Simon Hearne helps teams build fast search over unstructured data. He works at Zilliz, the company behind the Milvus open-source vector database, and writes and speaks about vector search, RAG pipelines, and search performance. Before that he spent over a decade as a web performance engineer and consultant, and is a regular conference speaker.

Canonical site: https://simonhearne.com/
Author page: https://simonhearne.com/about/
Every post below is also available as markdown by appending `index.md` to its URL.
Full text of all posts: https://simonhearne.com/llms-full.txt

## Talks

- [Vector Search, Visualised: Milvus Meetup Paris](https://simonhearne.com/2026/vector-search-visualised-paris/): A visual crash course in vector search, built around an ecommerce dress-finder: exact search, ANN indexes, quantisation, and the filters that quietly wreck your recall. (2026-10-07)
- [The RAG Cost Curve](https://simonhearne.com/2026/rag-cost-curve/): When does a retrieval index actually beat live search? Measured break-even points, not vendor claims: 334 queries a day on a short agent history, never on code the model already knows, and 24 on code… (2026-09-15)
- [Migrating to Milvus: Tooling, Deployment Choices and Lessons from Real Migrations](https://simonhearne.com/2026/migrating-to-milvus-talk/): How to move from Elasticsearch or OpenSearch to Milvus or Zilliz Cloud: migration tooling, a real end-to-end walkthrough, deployment choices, and lessons from real customer migrations. (2026-09-02)
- [Milvus 3.0: Closing the Search Gap](https://simonhearne.com/2026/milvus_search_gap/): Milvus 3.0 closes the gap between vector search and full-text search: one engine for both. A customer-backed comparison of Milvus 3.0 and Elasticsearch 9.14, with live side-by-side queries you can… (2026-08-19)
- [Vector Search, Visualised](https://simonhearne.com/2026/visualising-vector-search/): Vector search has no EXPLAIN. Through interactive visualisations, this talk shows what embeddings look like in high-dimensional space, what quantisation does to your recall, and how to catch… (2026-06-04)
- [WebPageTest Live: Third Parties and Request Map with Simon Hearne](https://simonhearne.com/2022/third-parties-request-map/): Third parties have always been a challenge. Having resources loading on your site, beyond your control isn't something users sign up for. In 2015, Simon Hearne created a tool called REQUEST MAP to… (2022-10-11)
- [An Inclusive Web is Fast by Default](https://simonhearne.com/2021/inclusive-design/): Web performance is critical to inclusive design - users on low-end devices or with poor connectivity are excluded from large and slow applications (2021-09-23)
- [The Psychology of Speed](https://simonhearne.com/2020/psychology-of-speed/): We intuitively know that faster is better, but what's the psychology and physiology behind it? (2020-10-15)
- [Deep dive into third-party performance](https://simonhearne.com/2019/third-party-deep/): A deep-dive into the impact of third-party tags on web performance. (2019-11-22)
- [Third-Party Content - the weak link?](https://simonhearne.com/2018/third-party-weak-links/): The Resource Timing API allows site owners to measure how third-parties perform for every single pageview. Combining this data with business intelligence provides new insight to the impact of… (2018-01-14)
- [Too hot to handle - optimizing for low powered devices](https://simonhearne.com/2016/too-hot-to-handle/): We know what web performance is—getting pages to render fast for as many customers as possible. Traditionally, the focus has been on the network, improving the time to deliver critical content, but… (2016-10-14)
- [Beyond the Waterfall - Meaningful Web Performance Visualizations](https://simonhearne.com/2016/meaningful-visualisations/): With all the different measurements we can take of web performance, the data we can report on becomes huge. Waterfall charts just don’t cut it any more – they are a technical tool to diagnose… (2016-10-14)
- [How fast is fast enough?](https://simonhearne.com/2016/how-fast-is-fast-enough/): Webinar with Andy Davies on measuring site speed and using RUM data to work out when performance starts to change customer behaviour. (2016-06-29)

## Blog posts


- [Haystack Europe 2026: the bleeding edge of retrieval engineering](https://simonhearne.com/2026/haystack-europe-2026/): Agents as search consumers, hybrid retrieval as the default, and how to evaluate search systems - a summary of my takeaways from Haystack Europe 2026. (2026-09-29)
- [Fast typeahead search with Milvus](https://simonhearne.com/2026/fast-typeahead-milvus/): Milvus can serve typeahead search recommendations in about 4ms, but only one or two of the obvious approaches get the answer right. I tested 36 query shapes on Milvus 3.0 so you don't have to. (2026-09-28)
- [Migrating Self-managed Milvus to Managed Milvus to gain >99% Performance](https://simonhearne.com/2026/migrating-milvus/): At small scale, self-managing a vector database is manageable. Once you're in the tens of millions of embeddings you'll probably want to offload the headache to a managed service. (2026-07-14)
- [Adding site search to Netlify sites using Elasticsearch](https://simonhearne.com/2024/netlify-elasticsearch/): A guide to implementing static site search using 11ty, Netlify and Elasticsearch (2024-05-07)
- [Optimising Core Web Vitals on SPAs](https://simonhearne.com/2022/core-web-vitals-on-spas/): Single-page applications present some unique challenges for measuring and optimising core web vitals, here we review the key optimisations you should be making for your SPA (2022-03-22)
- [Fixing empty responses from Cloudflare Workers Sites](https://simonhearne.com/2022/empty-responses-cloudflare-workers-sites/): A quick fix for empty response bodies on Cloudflare Workers Sites (2022-02-22)
- [Survivorship Bias in Web Performance](https://simonhearne.com/2022/survorship-bias-in-webperf/): Why your analytics shows your site as faster than it is, and why FCP is a key metric to optimise for. (2022-02-16)
- [The value of an independent web performance consultant](https://simonhearne.com/2022/value-of-a-consultant/): If you're wondering if you need an independent web performance consultant, this is why I think you do! (2022-02-04)
- [Caching Header Best Practices](https://simonhearne.com/2022/caching-header-best-practices/): Caching headers are surprisingly complex and often misconfigured. Here we look at some key cache scenarios and recommend the ideal headers to set. (2022-01-27)
- [Fast and Responsive Hero Videos for Great UX](https://simonhearne.com/2021/fast-responsive-videos/): Responsive landing page hero videos are increasingly popular, here we show how to make them as fast as possible. (2021-11-02)
- [Slow site speed is still the biggest cause of web stress](https://simonhearne.com/2021/web-stress/): It's something we've all felt before: the stress and anger induced when trying to use a frustratingly slow website or app. It's really hard to quantify this feeling though, and even harder to track… (2021-02-26)
- [Everything we know about Core Web Vitals and SEO](https://simonhearne.com/2021/core-web-vitals-seo/): There has been a lot of uncertainty and confusion since Google announced the Page Experience Update in 2020. In this post we will summarise everything we know about the update and the potential SEO… (2021-02-22)
- [How to avoid layout shifts caused by web fonts](https://simonhearne.com/2021/layout-shifts-webfonts/): One of the biggest causes of layout shifts for my clients is late-loading web fonts, let's look at how to optimise them! (2021-01-19)
- [Optimistic UI Patterns for Improved Perceived Performance](https://simonhearne.com/2021/optimistic-ui-patterns/): Speed is in the eye of the beholder, it is a perception of how fast an experience feels. Optimistic UI patterns can significantly improve perceived performance for relatively little effort. (2021-01-15)
- [Alternatives to Spinners on the Web](https://simonhearne.com/2020/alternatives-to-spinners/): Animated spinners are so 1999, there are some obvious and less-obvious alternatives to improve user experience. (2020-12-22)
- [Web Performance Predictions for 2021](https://simonhearne.com/2020/predictions-2021/): 2020 was a wild ride. Here are five key things to watch in the world of web performance in 2021! (2020-12-10)
- [The Impact of Let's Encrypt Changes on Android Users](https://simonhearne.com/2020/lets-encrypt-old-android/): Let's Encrypt will use its own root certificate in 2021, this may block access to 12% of Android users globally. (2020-11-09)
- [The Performance Cost of EV Certificates](https://simonhearne.com/2020/drop-ev-certs/): Extended Validation certificates are expensive and degrade performance. Move to an OV certificate if you can! (2020-11-04)
- [Getting Fast and Staying There](https://simonhearne.com/2020/getting-fast-staying-there/): Getting fast is difficult, staying fast even more so. How do successful companies ensure that their site speed stays at peak? (2020-10-27)
- [What is the best page speed metric?](https://simonhearne.com/2020/perf-metrics/): Out of the hundreds of available performance metrics, which ones make sense for you? (2020-10-26)
- [Four Charts That Prove the Value of Site Speed](https://simonhearne.com/2020/value-of-site-speed/): Site speed is critical to user experience and online success, here are four charts which prove the value! (2020-10-22)
- [How to Improve Core Web Vitals](https://simonhearne.com/2020/core-web-vitals/): Core Web Vitals are three new performance metrics which will soon impact SEO ranking. Learn how to measure and improve them to maximise user experience! (2020-10-19)
- [Giving Great (Remote) Software Demos](https://simonhearne.com/2020/great-demos/): Giving great software demos is both science and art. Here are some tips on making the most out of every demo opportunity, even when you're stuck at home! (2020-06-15)
- [Who Opts-in to Save-data?](https://simonhearne.com/2020/save-data/): A primer on save-data, what it means for your users and what it means for you. (2020-05-29)
- [Measuring Performance behind consent popups](https://simonhearne.com/2020/testing-behind-consent/): Opting in to cookies can load multiple megabytes of additional content. Here are tips on how to measure web performance both with and without cookie consent. (2020-05-13)
- [When Network is Faster than Cache](https://simonhearne.com/2020/network-faster-than-cache/): We assume that browser caches are near-instantaneous, but data shows that retrieving an object from cache can take hundreds of milliseconds! (2020-05-07)
- [Is it time for a Web Performance rebrand?](https://simonhearne.com/2020/web-performance-rebrand/): Web Performance is a niche term in a broad market, should we widen our appeal to reach more people? (2020-05-03)
- [Collecting SmartThings data in InfluxDB on Raspberry Pi](https://simonhearne.com/2020/pi-smartthings-influx/): How to collect data from your Home Automation system into a local timeseries database. (2020-01-07)
- [Collecting SpeedTest results in Influx on Raspberry Pi](https://simonhearne.com/2020/pi-speedtest-influx/): How to set up regular SpeedTest reports into a local InfluxDB on a Raspberry Pi (2020-01-07)
- [Reporting Raspberry Pi System Metrics to InfluxDB](https://simonhearne.com/2020/pi-metrics-influx/): How to set up regular system stat reports from a Raspberry Pi into a local InfluxDB (2020-01-07)
- [Installing InfluxDB & Grafana on Raspberry Pi](https://simonhearne.com/2020/pi-influx-grafana/): I recently treated myself to a RaspberryPi 4 Model B to use as a(nother) home server. This is a brief guide on getting InfluxDB and Grafana set up to store and graph timeseries data. (2020-01-07)
- [HTTP Headers for fast & secure static sites](https://simonhearne.com/2019/http-headers-fast-and-secure/): An introduction to key HTTP response headers for speed and security, with implementation guides for Netlify & CloudFlare (2019-12-10)
- [Six Web Performance Technologies to Watch in 2020](https://simonhearne.com/2019/2020-predictions/): Don't bet on 5G and HTTP/3 to make things faster, there are six technologies that I believe will have a bigger impact on web performance in 2020. (2019-11-25)
- [Native image lazy loading has landed in Chrome, maybe don't use it](https://simonhearne.com/2019/native-lazy-loading-in-chrome/): Native lazy loading for iframes and images landed in Chrome 76, but don't go ripping out your existing lazy loading strategy just yet. (2019-08-13)
- [WebPageTest Private - 'no successful results'](https://simonhearne.com/2019/wpt-private-no-successful-results/): A potential quick fix for "The test completed but there were no successful results." in WebPageTest private instances. (2019-08-09)
- [Why Site Speed is Critical for Online Publishers](https://simonhearne.com/2019/site-speed-for-publishers/): Site speed is a critical factor in the success of an online publishing business, whether revenue is driven by adverts or subscriptions. This post demonstrates the relationship between speed and… (2019-08-07)
- [Lead Developer Conference (London) - Day 1!](https://simonhearne.com/2018/leaddev-day-1/): Lead Developer is a conference for senior and lead software engineers. These are my raw notes from day one. (2018-06-27)
- [Delta V Conference - Day 2!](https://simonhearne.com/2018/deltav-day2/): Delta V Conference is a new two-day, single-track web performance conference in London, hosted by me, Perry Dyball and Jo Franchetti. Here's my raw notes from the fantastic content from our lovely… (2018-05-11)
- [Delta V Conference - Day 1!](https://simonhearne.com/2018/deltav-day1/): Delta V Conference is a new two-day, single-track web performance conference in London, hosted by me, Perry Dyball and Jo Franchetti. Here's my raw notes from the fantastic content from our lovely… (2018-05-10)
- [Twitter Lite isn't as good as the app, and that's okay](https://simonhearne.com/2017/twitter-pwa/): Twitter's Progressive Web App is finally out of testing, and it's not as good as the native app. Missing push notifications, wonky images, small text boxes, lack of sharing intents and confusing… (2017-04-07)
- [Your Analytics Lies to You](https://simonhearne.com/2017/analytics-lie/): You can't rely on your web analytics for performance data and it's understating bounce rate and traffic numbers from old devices. (2017-03-29)
- [How to Optimise CSS Image Sprites](https://simonhearne.com/2017/optimising-css-image-sprites/): Optimising sprites might be more important than you think, and easier than you expect! (2017-01-20)
- [Three WebPerf Takeaways from Velocity Europe](https://simonhearne.com/2016/three-takeaways-from-velocity/): Velocity Amsterdam has just come to a close. Here are the three key things that I am taking away from the two days of sessions. (2016-11-08)
- [Velocity NY 2016 - Wrap-up](https://simonhearne.com/2016/velocity-ny-2016-wrap-up/): Velocity New York seems like a distant memory now, especially with Velocity Europe around the corner. With that said, I have copious notes from the two day conference which I have summarised here.… (2016-10-11)
- [Blocking requests in webpagetest? Don't use Chrome.](https://simonhearne.com/2016/blocking-requests-in-webpagetest-dont-use-chrome/): We know that third-party content can harm the user experience on a website. Measuring that impact can be tricky. (2016-07-11)
- [Getting Reliable Visual Performance Metrics](https://simonhearne.com/2016/getting-reliable-visual-metrics/): Tips to get more reliable & consistent visual metrics from WebPageTest (2016-06-08)
- [Render Conf 2016](https://simonhearne.com/2016/render-conf-1/): Render Conference - previously known as jQuery UK - was held in Oxford last week. It's a front-end conference for front-end people, which makes me a bit of an outsider. Performance is not the focus… (2016-01-21)
- [Prioritising Site Speed Recommendations](https://simonhearne.com/2016/prioritising-sitespeed-recommendations/): Sometimes prioritising recommendations is more important than making them. (2016-01-18)
- [Velocity Europe 2015 - The Good Ones!](https://simonhearne.com/2015/velocity-europe-2015-report-2/): This post is a review and summary of the talks at Velocity Europe that I attended. I've summarised each talk and given links to the slides, videos and ratings. (2015-11-01)
- [Velocity Europe 2015 - My Allstars](https://simonhearne.com/2015/velocity-europe-2015-report-1/): This post is a review and summary of the talks at Velocity Europe that got a 5 star review from me. I've summarised each talk and given links to the slides, videos and ratings. (2015-11-01)
- [Measuring Webpage Jank](https://simonhearne.com/2015/jank-meter/): Webpage jank can harm the user experience, here's an easy way to measure it on your pages (2015-09-11)
- [Be Mindful With Modernizr](https://simonhearne.com/2015/be-mindful-with-modernizr/): Modernizr might be making your site slow, especially on mobiles (2015-08-10)
- [The Future of Web Performance - Part 1](https://simonhearne.com/2015/future-of-web-performance-1/): Web performance is critically important, how will upcoming technologies change the way we manage it? (2015-08-07)
- [Questions to Ask Your Third-Parties](https://simonhearne.com/2015/questions-to-ask-your-third-parties/): We need rules to keep third-party Javascript in check. (2015-07-03)
- [Manage Third-party Risk Using a Content Security Policy](https://simonhearne.com/2015/manage-3p-risk-csp/): A feature to prevent cross-site-scripting may make it easier to police third-party javascript. (2015-07-03)
- [Using a Web Performance Heatmap to Assess Page Performance](https://simonhearne.com/2015/performance-heatmap/): I've made a Heatmap to visualise when each element loads on a page. (2015-05-29)
- [How to Find the Third-Parties on Your Site](https://simonhearne.com/2015/find-third-party-assets/): Third-party means not you or me, but them. (2015-03-19)
- [Web Performance Optimisation Basics](https://simonhearne.com/2015/web-performance-optimisation-basics/): Website performance is critical to user experience. We need rules to make it easier. (2015-03-11)

## Feeds and machine-readable resources

- Atom feed: https://simonhearne.com/feed/feed.xml
- JSON Feed: https://simonhearne.com/feed/feed.json
- Talks JSON Feed (slides and video per talk): https://simonhearne.com/feed/talks.json
- Sitemap: https://simonhearne.com/sitemap.xml
- Full-text markdown: https://simonhearne.com/llms-full.txt

## Optional

- Tags index: https://simonhearne.com/tags/
- Slides: https://talks.simonhearne.com/