[Documentation] Add consolidated Performance Optimization Guide section

[SuryaGanesh284]

Description

The README.md currently contains valuable performance-related information scattered across different sections. This makes it challenging for users to quickly find and apply optimization techniques to improve their scrcpy experience.

Current State

Performance-related information is currently distributed across:

• "Must-know tips" section mentions --m1024 for reducing resolution
• Individual command examples show various flags without context
• Platform-specific optimizations are mentioned inline but not consolidated
• No clear guidance on which optimizations work best for different scenarios

Suggested Improvement

Add a dedicated "Performance Optimization" section that consolidates and organizes:

1. Resolution and Bitrate Optimization

• When and how to use --max-size / -m flag
• Recommended bitrate settings for different network conditions
• Trade-offs between quality and performance

2. Codec Selection

• H.264 vs H.265 performance comparison
• Platform-specific codec recommendations
• Hardware acceleration tips

3. Platform-Specific Optimizations

• Windows: Tips for best performance
• macOS: Metal acceleration notes
• Linux: X11 vs Wayland considerations

4. Network Optimization

• TCP vs AOA (USB) performance differences
• Wireless connection optimization tips
• Reducing latency for gaming/real-time use

5. Common Performance Issues

• Troubleshooting lag and stuttering
• Audio sync issues and solutions
• High CPU usage mitigation

Rationale

• Improved User Experience: Users can quickly find all performance tips in one place
• Reduced Duplicate Issues: Fewer performance-related questions in issues/discussions
• Better Onboarding: New users understand optimization options upfront
• Platform Parity: Ensures all platforms have documented optimization paths

Additional Context

This would especially benefit:

• Users with older/slower hardware
• Users on wireless connections
• Developers testing apps requiring low latency
• Streamers and content creators using scrcpy for demos

Example Structure

## Performance Optimization

### Quick Start: Common Optimizations
For most users, start with:
\`\`\`bash
scrcpy --max-size=1024 --video-codec=h264
\`\`\`

### Advanced Optimizations
...