Problem
Using the New Relic PHP agent in AWS Fargate results in poor performance.
Explanation
The PHP agent relies heavily on the clock source of a system for timing activities. Because of the constant clock checking, to be effective, the PHP agent needs a vDSO based clocksource so that the repetitive calls to check the time don't dominate the overall performance. You can find more details about how to check/change the clocksource here.
Unfortunately, AWS Fargate mandates the xen clocksource which does NOT support vDSO. Despite the availability of other clocksources, AWS Fargate prohibits you from changing the clocksource by making the sys directory read-only.
This is an open issue with Fargate regarding this limitation.
If Fargate is an absolute requirement, you could turn autoinstrumenting off and manually instrument only a few, key transactions. Other than this, because clocksource is so important for time checking to gather PHP metrics, there are currently no workarounds for this AWS issue. Some customers have found success using the agent on AWS services that allow you to change the clocksource, such as EC2 and Graviton.