Performance Degradation after AEM 6.5 LTS Upgrade | Community
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akhilraj
akhilraj
Level 5
April 22, 2026
Question

Performance Degradation after AEM 6.5 LTS Upgrade

  • April 22, 2026
  • 2 replies
  • 26 views

In our Adobe Experience Manager internal portal(Azure OIDC auth 6.5 instance) the homepage invokes a few APIs that fetch data from a database and store user-specific responses in Redis.

We normally conduct performance testing with 18,000 concurrent users (2 publishers with ~9,000 virtual users each) over a duration of 30 minutes. Prior to the upgrade, all API responses were consistently under 1 second.

Recently, we upgraded to AEM 6.5 LTS (SP21) running on Java 21. After the upgrade, under the same load conditions, the average API response time has increased significantly to around 11 seconds.

There are no functional issues observed, and all APIs are working as expected. However, this performance degradation is only noticeable during load testing.

Has anyone encountered similar performance issues after upgrading to AEM 6.5 LTS SP21 or moving to Java 21? Any insights or areas to investigate would be helpful.

2 replies

Mani_kumar_
Community Advisor
Mani_kumar_Community Advisor
Community Advisor
April 23, 2026

As this is happening after Java 21 upgrade check for the JVM flags before and after.

also analyze the heap dump with load run and modify the GC params accordingly this may fix or atleast better the performance.

S
Adobe Employee
SubbaraoGa1Adobe Employee
Adobe Employee
April 23, 2026

​@akhilraj We do not currently see Adobe documentation indicating a known general regression in AEM 6.5 LTS + Java 21 that would by itself explain the increase from sub-second responses to ~11 seconds under load. Adobe does, however, recommend explicit performance validation after upgrade and notes that Java 17/21 GC settings should be tuned for optimal performance rather than relying on defaults. Based on the current behavior, this appears more consistent with a load-sensitive tuning or integration issue involving JVM behavior, custom code, DB/Redis concurrency, or request/query execution under high load. [1] [2] [3]

[1] https://experienceleague.adobe.com/en/docs/experience-manager-65-lts/content/release-notes/service-pack/ga

[2]  https://experienceleague.adobe.com/en/docs/experience-manager-65-lts/content/implementing/deploying/practices/best-practices-for-performance-testing

[3] https://experienceleague.adobe.com/en/docs/experience-manager-65-lts/content/implementing/deploying/configuring/configuring-performance

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