Importing XML to Wordpress Always Get Error

I have server with 100 GB and 1 GB RAM. I install wordpress with Webuzo Panel. And setting max upload with 100MB max. But, when I upload a Blogger XML with 3 MB only, it will get Error with this error statement :

Network Error (tcp_error) 

A communication error occurred: "Operation timed out"
The Web Server may be down, too busy, or experiencing other problems preventing it from responding to requests. You may wish to try again at a later time.

How to setting the best setting for Server to get the best performance for wordpress in Centos Minimal 6 for wordpress. Any suggestion?