[v4] Improve performance of watch

[chan150]

When using isar v4, streaming performance of watch is extremely degraded since it needs to create stream controller.
To solve this issue, we utilize both watchLazy and findAll instead of allocating stream controller.

[vicenterusso]

Hello @chan150,

I'm interested in understanding the performance degradation. Could you come up with a small reproduction?

[chan150]

Here is a small reproduction:
https://github.com/chan150/isar_performance_degration_reproduction_example

2025-01-09.071016.mp4

[chan150]

Screen Refresh Rate Benchmark:

flutter: Improved watch (ms.): 29
flutter: Original watch (ms.): 1809
flutter: Improved watch (ms.): 14
flutter: Original watch (ms.): 2446
flutter: Improved watch (ms.): 13
flutter: Original watch (ms.): 2695
flutter: Improved watch (ms.): 16
flutter: Original watch (ms.): 2063
flutter: Improved watch (ms.): 12
flutter: Original watch (ms.): 2027
flutter: Improved watch (ms.): 8
flutter: Original watch (ms.): 2573
flutter: Improved watch (ms.): 8
flutter: Original watch (ms.): 2520
flutter: Improved watch (ms.): 9
flutter: Original watch (ms.): 1904
flutter: Improved watch (ms.): 11
flutter: Original watch (ms.): 2024
flutter: Improved watch (ms.): 9
flutter: Original watch (ms.): 2007
flutter: Improved watch (ms.): 11
flutter: Original watch (ms.): 2476