METR study: experienced open-source developers using Cursor, Claude, and other AI tools were 19% slower to complete tasks, despite thinking they were 20% faster
Study Shows That Even Experienced Developers Dramatically Overestimate Gains — The buzz about AI coding tools is unrelenting.
Second Thoughts Steve Newman
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- “When developers are allowed to use AI tools, they take 19% longer to complete issues—a significant slowdown that goes against developer beliefs and expert forecasts. This gap between perception and reality is striking: developers expected AI to speed them up by 24%, and even after experiencing the slowdown, they still believed AI had sped them up by 20%.” https://metr.org/... @hailey@hails.org · Hailey
- Study: When experienced open-source developers used current AI tools, work took 19% longer to complete. In spite of which, the developers *thought* they were working *faster. It's just one study, and they don't claim anything beyond what they observed. Their results are not predictive. Still.... … @zeldman@front-end.social · Zeldman
- 🚨For anyone thinking AI tools are always a shortcut to faster coding... think again. 🧠💻 … Yonas Bekele
- 🤯 METR study: AI makes expert developers 19% SLOWER — They tested 16 veterans on their own codebases (1M+ lines, 5+ years experience). … Fedir Skitsko
- I've feared for a long time that AI will slow down the most experienced, productive and talented people in the workforce. … Chris Baker
- I'm glad there's a study that backs up empirically what many of us have experienced anecdotally when using AI tools. — https://lnkd.in/... Adrian Booth
- Interesting observation by Gary Marcus about AI-assisted coding. It is a narrow case (senior engineers in a well-known complex environment) … Gerben Wierda
- The TLDR version: when vibe coding produces code that breaks, it takes time to fix it. — My experience with this is the same. … Sara Kubik
- AI coding tools can reduce productivity Hacker News
- Measuring the impact of AI on experienced open-source developer productivity Hacker News
- Not So Fast: AI Coding Tools Can Actually Reduce Productivity Lobsters
Discussion
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@adamjkucharski
Adam Kucharski
on bluesky
Interesting randomised controlled trial that found use of AI tools (i.e. Cursor) made developers about 20% slower on time-to-completion. Included a nice accompanying visualisation of possible reasons for discrepancies between RCT and other findings... metr.org/blog/2025-07... […
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@metr.org
@metr.org
on bluesky
We're exploring running experiments like this in other settings—if you're an open-source developer or company interested in understanding the impact of AI on your work, reach out to us here: forms.gle/pBsSo54VpmuQ... Paper: metr.org/Early_2025_A... Blog: metr.org/blog/2025-07..…
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r/programming
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on reddit
Not So Fast: AI Coding Tools Can Actually Reduce Productivity
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r/singularity
r
on reddit
Randomized control trial of developers solving real-life problems finds that developers who use “AI” tools are 19% slower than those who don't.
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r/slatestarcodex
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on reddit
METR finds that experienced open-source developers work 19% slower when using Early-2025 AI
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r/programming
r
on reddit
Measuring the Impact of AI on Experienced Open-Source Developer Productivity
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r/accelerate
r
on reddit
Measuring the Impact of Early-2025 AI on Experienced Open-Source Developer Productivity. The Results Might Surprise You!
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r/BetterOffline
r
on reddit
Measuring the Impact of Early-2025 AI on Experienced Open-Source Developer Productivity