An alternative to fake users or test environments is to run performance tests on your real live environment using genuine users as they interact with your web application. You can use feature switching to gradually roll out a new feature to a small subset of your user base and monitor the system for excessive load. If everything seems normal, then you can continue the rollout; otherwise, you can rollback.
You may hear similar ideas referred to by other names, such as feature flags, feature toggles, canary releases, or branch by abstraction. Some of these may have subtly different meanings, but the general guiding principle of gradually releasing a change is much the same.
The following diagram shows how you could progressively ...
