Critically Slow Avatar Initialization (10-60 sec) for v1/streaming.new Sequential Calls

Issue Description:
We're experiencing unacceptably long processing times (10-60 seconds) for v1/streaming.new API calls during sequential avatar initialization. The issue is consistently reproducible with 10+ consecutive calls.

Critical Evidence:
The problem persists even when using your official "Try It!" tool in the documentation:

Visit: https://docs.heygen.com/reference/new-session
Enter valid API key
Send standard request

{
  "avatar_name": "4a4323335b244f5fa7750b8b0e69f2b6",
  "quality": "high",
  "voice": {
    "rate": 0.5,
    "emotion": "broadcaster",
    "elevenlabs_settings": {}
  },
  "language": "ru",
  "version": "v2",
  "video_encoding": "H264",
  "source": "sdk",
  "ia_is_livekit_transport": true
}

Result: Execution time frequently exceeds 15-30 seconds

Test Metrics:

# 10 sequential streaming.new calls
Request 1: 3.4 sec
Request 2: 6.7 sec
Request 3: 7.1 sec
Request 4: 3.8 sec
Request 5: 34.5 sec  # Peak value
Request 6: 27.3 sec
...
Average: 19.2 sec

Business Impact:

Users wait >15 seconds for avatar initialization

30% mobile connection timeouts

Inability to provide smooth UX

Conversion loss during onboarding

Eastern Europe region (ojerusalem1a (1649 km))