You must first determine your requirements. Users want fast response times, typically less than 100 milliseconds, high availability with no connection refused messages, and significant control. Webmasters and proxy server administrators, on the other hand, need high connection rates, high data throughput, and uptime approaching 100%. You need to define what performance means for your particular situation based on your requirement.
The following factors have an impact on performance:
The Number of peak concurrent users
Encrypting your proxy server’s data streams with SSL makes an enormous difference to your site’s credibility for electronic commerce and other security conscious applications, but can seriously impact your CPU load. For more information, see SSL Performance.
Disk Cache hits or misses
A high percentage of cache hits indicate efficient utilization of cached objects, which in turn leads to improved performances.
Custom configurations to increase cache efficiency
You can configure Proxy Server to increase cache efficiency, and performance, at the cost of spec-compliance. For example, you can have configurations that ignores page reload requests , or those that ignore cache directives in response headers that do not allow caching the response.
Disk cache location
Using RAM-based file systems to hold the disk cache can significantly improve performance.
Care should be taken to ensure that hardware factors such as network speed and disk throughput match the processing power of the CPU as well as the request handling capacity of the proxy server.
Behavior of origin servers
The origin servers response time has a crucial effect on the proxy server's performance numbers.