Improve Session Replay performance on iOS

[falk-stefan]

OS:

• Windows
• MacOS
• Linux (Ubuntu)

Platform:

• iOS
• Android

SDK:

• @sentry/react-native (>= 1.0.0)
• react-native-sentry (<= 0.43.2)

SDK version: 5.26.0

react-native version: 0.74.3

Are you using Expo?

• Yes
• No

Are you using sentry.io or on-premise?

• sentry.io (SaaS)
• on-premise

Configuration:

(@sentry/react-native)

Sentry.init({
  environment: environment.env,
  dsn: environment.sentry.dsn,
  sampleRate: environment.env === 'production' ? 0.05 : 1.0,
  tracePropagationTargets: [environment.apiUrl],
  _experiments: {
    // Currently under _experiments for 5.26.0-alpha releases
    replaysSessionSampleRate: 0.01,
    replaysOnErrorSampleRate: 1.0,
  },
  defaultIntegrations: [
    Sentry.mobileReplayIntegration({
      maskAllText: false,
      maskAllImages: false,
    }),
  ],
});

---

I have the following issue:

For testing, I have two phones available. One Galaxy A33 5G and an iPhone X.

After making my first iOS build I noticed that the application way really slow. Scrolling would sometimes completely getting stuck on the iOS device. However, I didn't have any issues on the Android device.

Long story short: After some thinking what the issue might be, I removed the Sentry.mobileReplayIntegration and noticed that the iPhone X was able to perform normally.

I am not sure if this is due to the device being comparatively old. However, the iPhone X isn't terribly weak. Not sure if this can be improved but I thought I'd just bring it up here just in case this isn't a known issue.

Expected result:

No significant performance impact.

[brustolin]

Hello @falk-stefan Thanks for reaching out.

We will investigate the impact on performance.
Were you testing this on debug alone, or did you try a release build?

I removed the Sentry.mobileReplayIntegration and noticed that the iPhone X was able to perform normally.

You mean, when the redact was enabled, there were no performance issues?

[falk-stefan]

Hi!

Were you testing this on debug alone, or did you try a release build?

I used an internal ad-hoc build on a physical iPhone X.

You mean, when the redact was enabled, there were no performance issues?

Essentially, I just commented out the entire section in order to remove the integration like so:

Sentry.init({
  environment: environment.env,
  dsn: environment.sentry.dsn,
  sampleRate: environment.env === 'production' ? 0.05 : 1.0,
  tracePropagationTargets: [environment.apiUrl],
  // _experiments: {
  //   // Currently under _experiments for 5.26.0-alpha releases
  //   replaysSessionSampleRate: 0.01,
  //   replaysOnErrorSampleRate: 1.0,
  // },
  // defaultIntegrations: [
  //   Sentry.mobileReplayIntegration({
  //     maskAllText: false,
  //     maskAllImages: false,
  //   }),
  // ],
});

After installing a new ad-hoc build on the device, the performance was back to normal.

[brustolin]

Essentially, I just commented out the entire section in order to remove the integration like so

Ok, so you disabled session replay completely.
Thanks for the answers!