firestore_client.cc: increase the kRegularBackfillDelay from 1ms to 1000ms (#10170)

Author: dconeybe

Firestore/CHANGELOG.md

@@ -1,6 +1,7 @@
 # Unreleased
 - [added] Expose client side indexing feature with `FIRFirestore.setIndexConfigurationFromJSON` and
   `FIRFirestore.setIndexConfigurationFromStream` (#10090).
+- [fixed] Fixed high CPU usage whenever Firestore was in use (#10168).
 
 # 9.5.0
 - [fixed] Fixed an intermittent crash if `ListenerRegistration::Remove()` was

Firestore/core/src/core/firestore_client.cc

@@ -113,7 +113,7 @@ static const auto kRegularGCDelay = std::chrono::minutes(5);
 /** How long we wait to try running index backfill after SDK initialization. */
 static const auto kInitialBackfillDelay = std::chrono::milliseconds(15);
 /** Minimum amount of time between backfill checks, after the first one. */
-static const auto kRegularBackfillDelay = std::chrono::milliseconds(1);
+static const auto kRegularBackfillDelay = std::chrono::milliseconds(1000);
 
 }  // namespace