[CameraKit Web SDK - v0.22.0](../README.md) / [Exports](../modules.md) / LensPerformanceMetrics

# Class: LensPerformanceMetrics

Use to measure lens rendering performance.

The [LensPerformanceMetrics.beginMeasurement](LensPerformanceMetrics.md#beginmeasurement) method is used to start measuring rendering performance. After
a measurement has begun, performance metrics can be read using [LensPerformanceMeasurement](LensPerformanceMeasurement.md).

**`Example`**

```ts
const measurement = cameraKitSession.metrics.beginMeasurement()
// some time later
console.log(measurement.measure())
```

## Table of contents

### Methods

- [beginMeasurement](LensPerformanceMetrics.md#beginmeasurement)

## Methods

### beginMeasurement

▸ **beginMeasurement**(): [`LensPerformanceMeasurement`](LensPerformanceMeasurement.md)

Begin a measurement window, during which time rendering metrics will be gathered.

#### Returns

[`LensPerformanceMeasurement`](LensPerformanceMeasurement.md)

A [LensPerformanceMeasurement](LensPerformanceMeasurement.md) representing an ongoing measurement of aggregated rendering
metrics, from which specific metrics can be obtained.