PostgreSQL Performance Tuning

I need an experienced PostgreSQL expert to resolve performance degradation issues during peak usage times.

Peak usage involves:
- High volume of data writes
- Large number of read queries
- Complex transactions/operations

Ideal skills and experience:
- Expertise in PostgreSQL performance tuning
- Experience with high-volume data operations
- Strong understanding of complex queries and transactions
- Ability to identify and resolve bottlenecks

Please provide a detailed approach and relevant experience in your bids.