---
title: "Discussion on \"Hidden CPU Burn: How Scalar User-Defined Functions Trap Your Queries in RBAR Loops\" | Hashnode"
description: "Discussion on \"Hidden CPU Burn: How Scalar User-Defined Functions Trap Your Queries in RBAR Loops\". Unwrapping row-by-row bottlenecks: Why modular code kills database performance, how to track hidden UDF execution penalties, and how to convert functions into high-speed inline expressions."
url: "https://hashnode.com/posts/hidden-cpu-burn-how-scalar-user-defined-functions-trap-your-queries-in-rbar-loops/6a4559d98141cde67a842b91"
---

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# [Hidden CPU Burn: How Scalar User-Defined Functions Trap Your Queries in RBAR Loops](https://tunedinstance.com/hidden-cpu-burn-how-scalar-user-defined-functions-trap-your-queries-in-rbar-loops?utm_source=hashnode&utm_medium=feed)

Unwrapping row-by-row bottlenecks: Why modular code kills database performance, how to track hidden UDF execution penalties, and how to convert functions into high-speed inline expressions.

Jul 1 · 6 min read · tunedinstance.com  
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## Written by

[Rakesh Kishore](https://hashnode.com/@RakeshKishore)

@RakeshKishore · Hyderabad, India

  
[View profile](https://hashnode.com/@RakeshKishore)

Sharing a decade of database lessons, failures, and fixes.

Senior Database Administrator specializing in SQL Server core internals, high-concurrency optimization, and enterprise database architecture. Over the last decade, my focus has been on mastering and breaking down complex database engine mechanics—from B-Tree performance tuning and TempDB allocation contention to deploying resilient cloud database infrastructure and high-availability clusters. I write at TunedInstance.com to share real-world production triage, architectural blueprints, and deep-dive technical strategies to keep mission-critical workloads fast, secure, and highly available.

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