SQL Server 2025 known issues update (#36643)

Updated the link format for the 'Persisted statistics for readable secondary replicas' feature in the known issues documentation.

Author: thesqlsith

docs/sql-server/sql-server-2025-known-issues.md

@@ -4,7 +4,7 @@ description: Known issues, causes, and workarounds for SQL Server 2025 (17.x), c
 author: MikeRayMSFT
 ms.author: mikeray
 ms.reviewer: randolphwest
-ms.date: 02/11/2026
+ms.date: 02/18/2026
 ms.service: sql
 ms.subservice: release-landing
 ms.topic: troubleshooting-known-issue
@@ -36,6 +36,7 @@ The following issues are currently identified:
 - [Upgrade fails if Data Quality Services is installed](#upgrade-fails-if-data-quality-services-is-installed)
 - [Full-Text Search fails to index plaintext documents larger than 25 MB](#full-text-search-fails-to-index-plaintext-documents-larger-than-25-mb)
 - [Incorrect license agreement for LocalDB installer](#incorrect-license-agreement-for-localdb-installer)
+- [SQL Server might become slow or unresponsive after creating or bringing online a large number of databases](#sql-server-might-become-slow-or-unresponsive-after-creating-or-bringing-online-a-large-number-of-databases)
 
 ## SQL Server 2025 installation fails when TLS 1.2 is disabled
 
@@ -210,6 +211,14 @@ To work around this issue, you must download the Express edition installer inste
 
 We have identified a fix for a future release of [!INCLUDE [sssql25-md](../includes/sssql25-md.md)].
 
+## SQL Server might become slow or unresponsive after creating or bringing online a large number of databases
+
+**Issue**: This behavior is caused by a per database background worker thread created as part of the [Persisted statistics for readable secondary replicas](../relational-databases/performance/persisted-stats-secondary-replicas.md) feature. This feature is enabled by default in [!INCLUDE [sssql25-md](../includes/sssql25-md.md)]. The background thread is created when databases come online and can cause worker thread pressure and reduced instance responsiveness, even when no secondary replicas are configured.
+
+**Workaround**: Enable startup [trace flag 15608](../t-sql/database-console-commands/dbcc-traceon-trace-flags-transact-sql.md#tf15608) and restart [!INCLUDE [ssnoversion-md](../includes/ssnoversion-md.md)]. You must enable the trace flag at startup. Enabling it after startup doesn't stop background threads that are already created for databases that were brought online. In scenarios with no secondary replicas, this trace flag is still required as a temporary mitigation to prevent the per database background thread from being created during database startup.
+
+A fix is planned for a future update of [!INCLUDE [sssql25-md](../includes/sssql25-md.md)].
+
 ## Related content
 
 - [What's new in SQL Server 2025](what-s-new-in-sql-server-2025.md)