Recently, I spent a bit of time running performance tests against various versions of CQ5/AEM to understand the performance characteristics of the different versions. One of the interesting outcomes of this testing is that CQ 5.6 and before have a very distinct point at which the instance becomes unstable.
To evaluate the performance characteristics of AEM, I used an AWS m4.xLarge EC2 instance and Apache Benchmark to simulate traffic against a consistent baseline.
AEM 6.0 and 6.1 were able to scale up to 1000 concurrent requests without significant errors as illustrated in the graph below:
CQ5.6 however ran into serious problems at approximately 400 concurrent requests and experienced a high and increasing error rate as the concurrency continued to increase.
So why is this the case? In AEM 6.0, Adobe introduce the new CRX3 repository which is based on Jackrabbit OAK. This new repository implementation provides significant performance improvements over CRX2.
I found out a number of other particularities when comparing the performance of CQ 5.6 and AEM 6.1, for a complete report, including analysis and recommendations: