The CPU continues to be consumed for as many active GADNativeAd instances.

[Kazumasa Shimomura]

Hello.
I am loading multiple native ads using GADAdLoader. The loaded GADNativeAds are stored in an array as properties within the class.

Even if they are not displayed on the screen, simply holding the instances results in CPU usage. Generally, 5 instances cause the main thread to continue using 20%. In my app, since I load and hold 15 ads, it consistently uses 60%. I confirmed this by debugging on an actual device.

Additionally, when checking with Instruments, it appears that AVAudioSession.currentRoute is being checked approximately every 0.2 seconds, which seems to be the cause. Is it being checked by GADNativeAd? Is it possible to disable this or to get a fix for it?

I believe this has been occurring since quite an earlier version. I confirmed that it happens with both version 11.5.0 of the Google-Mobile-Ads-SDK and the latest version 11.9.0. I am using CocoaPods for installation.

For reference, I also checked the example repository and observed the same phenomenon. In the example code, the held instance is only one, so the impact is minimal, but when modified to load and hold multiple instances, it occurs.

```swift
// let options = GADMultipleAdsAdLoaderOptions()
// options.numberOfAds = 5
```

https://github.com/googleads/googleads-mobile-ios-examples/tree/main/Swift/advanced/SwiftUIDemo/SwiftUIDemo/Native

I would appreciate it if you could investigate this issue when you have time.