Pegasaas Accelerator is NOT compatible with “mod_pagespeed” installed on the server. Do not run “mod_pagespeed” with Pegasaas Accelerator installed.
In most situations, websites running with Ngnix running as a proxy to Apache are compatible with Pegasaas. There is a rare known case when the size of the web page can exceed the size of buffer allowed by Ngnix. In these situations, you will get a 500 server error when viewing the web page on the front end. The only known solution is to increase the buffer size in ngnix by adding the following directives:
fastcgi_buffers 16 16k; fastcgi_buffer_size 32k; proxy_buffer_size 128k; proxy_buffers 4 256k; proxy_busy_buffers_size 256k;