Performance Regression Observed on SQL Server 2025 Running on Windows Server 2025

Question

Performance Regression Observed on SQL Server 2025 Running on Windows Server 2025

V, Priyadharshini (FT D AA IN SB PRO SEC) 0

A reproducible performance degradation is observed when executing an identical SQL workload through SQL Server Management Studio (SSMS) on SQL Server 2025 running on Windows Server 2025.

The workload consists of inserting 200,000 records into a table using repeated INSERT statements. The execution time on SQL Server 2025 + Windows Server 2025 is significantly slower compared to equivalent environments using SQL Server 2022.

The issue is consistently observed on virtual machines hosted in OpenShift, while equivalent virtual machines hosted on Hyper-V complete the workload significantly faster.

Configurations Tested

The following combinations do not demonstrate the same performance issue:

SQL Server 2022 + Windows Server 2022 SQL Server 2022 + Windows Server 2025 SQL Server 2025 + Windows Server 2022

The performance degradation is primarily observed with:

SQL Server 2025 + Windows Server 2025 (OpenShift VM) Test Scenario SQL script executed manually through SSMS. Same SQL script executed across all environments. 200,000 rows inserted into the same table. Same database schema. Same test methodology. Multiple executions performed with consistent results. Performance Results SQL Server 2025 + Windows Server 2025 OpenShift VM Records Inserted: 200,000 Elapsed Time: 249.875 seconds Throughput: 800 rows/second Average Row Insert Time: 1.249 ms Hyper-V VM Records Inserted: 200,000 Elapsed Time: 65.034 seconds Throughput: 3075 rows/second Average Row Insert Time: 0.325 ms Observation

The OpenShift environment requires approximately 3.8 times longer to complete the same workload compared to the Hyper-V environment.

Troubleshooting Performed

The following items have been validated or tested:

Database Compatibility Level: Database compatibility level reviewed. Tested with the expected compatibility(150,160) configuration.No significant improvement observed. Query Execution: Same SQL script executed across environments. SQL Server Configuration: SQL Server configuration reviewed.No configuration differences identified that explain the observed degradation. Authentication :Kerberos and authentication behavior reviewed.No authentication failures observed. No SSPI-related errors observed during workload execution. Encryption:SQL Server Force Encryption setting tested. Tuning off force encryption also didnt give any improvement.Workloads executed with encryption-related settings reviewed. TLS Investigation: TLS-related configuration reviewed.No Schannel warnings or TLS negotiation failures observed.

Workload tested on:

Hyper-V virtual machines
OpenShift virtual machines

Hyper-V environment performs as expected.

Performance degradation is primarily observed on OpenShift-hosted Windows Server 2025 virtual machines running SQL Server 2025.

Application Layer Workload reproduced directly in SSMS. Issue is not dependent on application code. Application layer removed from test scenario. Request for Investigation

We request assistance in determining whether this behavior is related to:

A known SQL Server 2025 performance regression. A known Windows Server 2025 performance regression. An interaction between SQL Server 2025 and Windows Server 2025. A virtualization-related issue specific to OpenShift-hosted Windows Server 2025 virtual machines. Any changes in SQL Server 2025 affecting row-by-row insert workloads.

Please advise on additional diagnostics, traces, ETW captures, PerfMon collections, SQL LogScout data, or dump collection requirements needed for further investigation.

I would also add one more line because it is very important:

The workload slowdown is reproducible directly from SSMS without involving the application layer, indicating that the issue can be reproduced using SQL statements alone.

That single sentence immediately tells Microsoft support that they don't need your product installed to reproduce the issue.

Erland Sommarskog 137.9K Reputation points MVP Volunteer Moderator

2026-10-07T13:19:57.52+00:00

If you want Microsoft to investigate this, you need to open a support request. This is a forum monitored by volunteers like me, and occasionally people from companies that provide support on behalf of Microsoft. However, for a thorough investigation of the case, you would need escalation to the product groups, and that can only happen through a support case. (And, I suspect, only if you have a support contracts that permits for this.)

An important point here is how far Microsoft support OpenShift, it seems that this is quite an important point here.

How do these scripts look like? You say that "inserting 200,000 records into a table using repeated INSERT statements." But do they insert one row at a time, or does each INSERT statement insert a number of rows at the same time. Are there any transactions in the script?

Your answer

Erland Sommarskog 137.9K Reputation points MVP Volunteer Moderator

2026-10-07T13:19:57.52+00:00

If you want Microsoft to investigate this, you need to open a support request. This is a forum monitored by volunteers like me, and occasionally people from companies that provide support on behalf of Microsoft. However, for a thorough investigation of the case, you would need escalation to the product groups, and that can only happen through a support case. (And, I suspect, only if you have a support contracts that permits for this.)

An important point here is how far Microsoft support OpenShift, it seems that this is quite an important point here.

How do these scripts look like? You say that "inserting 200,000 records into a table using repeated INSERT statements." But do they insert one row at a time, or does each INSERT statement insert a number of rows at the same time. Are there any transactions in the script?