Reduce first impression latency

  • Long waterfall mediation chains can increase ad request latency, potentially preventing ads from showing.

  • Reduce first impression latency by setting an initialization timeout to prevent exceeding a defined time limit.

  • Remove waterfall ad sources from your first ad request by implementing key-value segmentation and prioritizing a bidding-only mediation group.

  • Improve performance on less time-sensitive impressions by using ad preloading with an ad request that doesn't target the bidding-only mediation group.
Select platform: Android iOS Unity Android (Legacy)

Initializing an app with long waterfall mediation chains and multiple third party adapters can increase ad request latency for critical impressions that show first in the user's session. This increased first impression latency can prevent the ad from showing as the ad request has not yet returned a response.

This guide covers the following to reduce first impression latency in your app sessions:

Before you begin

Before you continue, set up Google Mobile Ads SDK (Legacy).

Set an initialization timeout

To avoid missing an impression opportunity, set an initialization timeout. This approach prevents your app from exceeding the time limit you defined. You can proceed with the ad request after the time limit you set, or after initialization completes.

The following example sets an initialization timeout of five seconds:

Kotlin


// Set up a CONFLATED channel that only buffers the latest event.
private val adLoadChannel = Channel<Unit>(Channel.CONFLATED)

fun initialize(context: Context) {
  // Coroutine to handle the 5-second timeout.
  CoroutineScope(Dispatchers.Default).launch {
    delay(5000L)

    // 5 second timer elapsed
    adLoadChannel.trySend(Unit)
  }

  // Coroutine to call MobileAds.initialize() on a background thread.
  CoroutineScope(Dispatchers.IO).launch {
    MobileAds.initialize(context) {
      // Mobile Ads SDK initialization finished.
      adLoadChannel.trySend(Unit)
    }
  }

  // Coroutine to listen for init complete or timer, whichever comes first.
  CoroutineScope(Dispatchers.Main).launch {
    // Wait on the first event.
    adLoadChannel.receive()
    loadAd()
    // Close the channel after receiving the first event.
    adLoadChannel.close()
  }
}

Remove waterfall ad sources on your first request

To deliver ads without any additional latency from waterfall ad sources, implement key-value segmentation to remove waterfall ad sources on your first ad request. Complete the following steps:

  1. Create a mediation group and add bidding ad sources.
  2. Add key-value segmentation to your new bidding-only mediation group using key latency and value low.
  3. Prioritize your new bidding-only mediation group above your primary mediation group in the UI. To adjust the order, change mediation group priority.

  4. In your first ad request, include the custom targeting key-value pair:

    Kotlin

    val request = AdRequest.Builder()
    .addCustomTargeting("latency", "low")
    .build()

    Java

    AdRequest request = new AdRequest.Builder()
    .addCustomTargeting("latency", "low")
    .build();

  5. Test the key-value segmentation setup to verify you are correctly targeting the new bidding-only mediation group.

Improve performance on less time-sensitive impressions

To improve performance on less time-sensitive impressions, such as ads that don't need to show right at app launch, use ad preloading with an ad request that does not target the bidding-only mediation group.