Foojay Podcast #84: Developing Performant, Cost Efficient, and Eco-friendly code
- December 01, 2025
- 157 Unique Views
- 2 min read
In this Foojay Podcast, we're exploring a critical topic that's becoming increasingly important in our industry: developing sustainable software that is both performant and environmentally friendly.
At the Devoxx and JFall conferences, I had fascinating conversations about how we as Java developers can make a real impact on both our cloud costs and our carbon footprint. And it's interesting to learn how these two goals are often perfectly aligned: what's good for your budget is usually good for the planet too.
We start with Daniel Witkowski. He published an article on Foojay that takes us on a deep dive into performance tuning. He explains why optimizing your code can have a thousand times more impact than saving 30% on cloud costs, and walks us through his journey of turning a simple integer validation challenge into a masterclass on Java performance optimization.
Next, I caught up with Ko Turk, who shares his passion for sustainable engineering and space exploration. He introduces us to Kepler, a tool for monitoring the energy consumption of your applications, and explains how performance optimization naturally leads to sustainability improvements.
Then Ronald Dehuysser, founder of JobRunr, reveals how his open-source job-scheduling library now enables carbon-aware job processing. He explains how JobRunr can automatically schedule non-time-critical jobs to run when renewable energy is most available.
And finally, Jan Ouwens joins us to discuss practical strategies for reducing both costs and CO2 emissions in your applications. He explains why cloud spending is actually a good proxy for your carbon footprint.
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Content
00:00 Introduction of topic and guests
02:07 Daniel Witkowski
- https://www.linkedin.com/in/danielwitkowski
- https://foojay.io/today/the-art-of-performance-tuning-why-saving-30-in-the-cloud-means-nothing-if-your-code-wastes-1000x-more/
- https://foojay.io/today/foojay-podcast-83/
- Why Saving 30% in the Cloud Means Nothing if Your Code Wastes 1000× More
- Performance tuning is less about syntax and more about craftsmanship.
29:46 Ko Turk
- https://www.linkedin.com/in/ko-turk-b271b929/
- https://github.com/sustainable-computing-io/kepler
- Sustainable engineering
- Kubernetes Efficient Power Level Exporter (Kepler)
32:46 Ronald Dehuysser
- https://www.linkedin.com/in/ronalddehuysser/
- https://www.jobrunr.io/en/
- Carbon-aware job processing with JobRunr
- Growing from an open-source project to a company
37:36 Jan Ouwens
- https://www.linkedin.com/in/janouwens/
- https://jqno.nl/
- Reducing the cost and CO2-emissions of your application
- Private cloud versus cloud providers
45:14 Outro
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Principal Sales Engineer at Azul with over 20 years of experience in software engineering, performance tuning, and technical consulting — with the last decade dedicated to helping enterprises across EMEA and globally get the most out of the Java platform.
Frank Delporte is a Java Champion, Java Developer, Technical Writer at Azul, Blogger, Author of "Getting started with Java on Raspberry Pi", and Pi4J Contributor. Frank blogs about his experiments with Java and JavaFX, sometimes combined with electronic components, on the Raspberry Pi.
⚡️Voxxed Days Amsterdam Organiser 👭 CodelabJUG 🗣 Speaker ✔ Software Architect @CodeLab 🍀 Green Software Champion
Meet Ronald Dehuysser, a software architect from Belgium and creator of JobRunr. Seamlessly integrating with Spring Boot, Micronaut, and Quarkus, JobRunr is an easy solution for efficient distributed background job processing and scheduling. When he's not working on open-source software, he is probably either rock climbing or sipping a fine Belgian Duvel beer.
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