---
title: "Dapper query slows down after the first few requests — parameter sniffing?"  
description: "Dapper query slows down after the first few requests — parameter sniffing?"  
author: "Lily Chitlangiya"  
published: 2026-09-30  
updated: 2026-09-30  
canonical: https://www.mindstick.com/forum/162226/dapper-query-slows-down-after-the-first-few-requests-parameter-sniffing  
category: "Performance"  
tags: ["Dapper", "asp.net core", "Performance Tuning", "sql server"]  
reading_time: 1 minute  

---

# Dapper query slows down after the first few requests — parameter sniffing?

We're seeing a strange pattern in production: the first call to a Dapper-backed endpoint is instant, but the next few within the same minute crawl. SQL Server 2019, same query plan every time according to the actual execution plan.

I enabled `SET STATISTICS IO, TIME ON` and logical reads jump after the initial execution. Could parameter sniffing be locking the optimizer onto a bad plan from the first parameter set? We don't use `OPTION (RECOMPILE)`. Is there a lightweight way to diagnose or mitigate this without rewriting the whole data layer?


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Original Source: https://www.mindstick.com/forum/162226/dapper-query-slows-down-after-the-first-few-requests-parameter-sniffing

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