Staff Engineer · Performance Engineering
Elena Tănăsoiu
Making one of the world's largest Ruby on Rails applications faster at GitHub. Profiling production traffic, diagnosing bottlenecks, and occasionally convincing teams they don't need more hardware.
She has a fondness for flamegraphs because they remove the guesswork.
01. About
I'm a Staff Engineer on GitHub's Performance Engineering team, where I spend my days profiling production traffic, diagnosing bottlenecks, and making one of the world's largest Ruby on Rails applications faster.
My journey in tech started in Bucharest, Romania and took me through London's vibrant Ruby community. I've grown from writing my first RSpec tests to leading performance investigations that save millions of CPU cycles across GitHub's infrastructure.
When I'm not staring at flamegraphs, you'll find me knitting, painting, making terrible puns, or exploring the great outdoors.
Things I work with
- ▸ Ruby / Rails
- ▸ Go
- ▸ Flamegraphs
- ▸ Caching at Scale
- ▸ Observability
- ▸ Performance
- ▸ MySQL
02. Speaking
Upcoming
Flamegraphs Workshop
Lead Dev London
An 80-minute hands-on workshop on using flamegraphs to diagnose and fix performance bottlenecks in production applications.
Performance Engineering for Everyone
Brighton Ruby
A real production story about how profiling a single page cut CPU consumption by 13%.
Co-presented with Emma Gabriel, Sr. Director at GitHub
Past
Service Modeling at GitHub
Friendly.rb · September 2023
Keynote. How GitHub models and monitors its services at scale to keep the platform reliable.
An RSpec Primer: Increase Your Quality of Life
LRUG · November 2018
A practical introduction to writing better RSpec tests and making the testing experience enjoyable.
03. Blog
27 March 2025
How Removing One Query Cut a Page's CPU by 23%
A flamegraph revealed an unnecessary search query on one of GitHub's most visited pages. The fix was 12 lines added, 65 deleted.
Read more →18 March 2025
A Gentle Introduction to Flamegraphs
What flamegraphs are, how to read them, and why they've become my favourite tool for understanding where time is actually spent in production.
Read more →9 January 2025
Running Science Experiments in Production with Scientist
How Scientist experiments work, and why I contributed CPU time tracking to the gem.
Read more →04. Creative Writing
Sometimes I write fiction. Here's what happens when a software engineer picks up a pen.