In my point of view the magento is only best plateform for E-commerce site and is more secure and shows a good performance and their benefits are,
1. High availability: Retain existing customer
2. Scalability: Add the number of new customers
3. Central management: Better support to the customers
4. Enable opcode cache, for example APC or Zend Guard this will increase load speed of php.
5. New releases often include performance improvements and other patches which affects performance.