Performance optimization¶

Most of what makes a ReactiveUI app fast is not specific to ReactiveUI: it is the stream itself. The Primitives best practices page covers marking lambdas static, sharing expensive work, filtering to real changes, and the other habits that apply to any stream built on ReactiveUI.Primitives.

Two habits are specific to building a ReactiveUI view model:

• Marshal to the UI thread only where a value reaches a bound property, not at every step in a chain. See UI thread and schedulers and only one WitnessOn per chain.
• Let WhenActivated stop a view model's subscriptions while its view is off screen. A background timer or a polling stream then stops running for a screen nobody is looking at. See when activated.