SQL Database Optimization Expert Needed

I'm looking for a Database Engineer to help me optimise my SQL database. Both read and write operations are currently slow and I need the performance improved for a mixed workload.

The ideal candidate should have:
- Extensive experience with SQL databases
- Proven track record in database performance optimization
- Ability to understand and improve performance for mixed workloads
- Strong analytical skills to diagnose issues and implement solutions

Please provide examples of previous similar projects you've undertaken.