WebSite Load Testing

I am looking for someone who can perform a thorough load test of my website. The idea is to ensure its performance remains consistent under high traffic and to identify any bottlenecks or performance issues. The testing will need to simulate an average of 100-500 concurrent users and focus primarily on stress testing the shopping cart and checkout process. Skills and experiences required would include expertise in load testing, a sound knowledge of e-commerce processes and an ability to recommend solutions to optimize server performance.