After installation the opac was getting just 3 points with regard to site speed here:
https://developers.google.com/pagespeed/ Then I enabled compression in the server.xml file of apache tomcat. Then the Google page speed gave 80 points. A huge difference. Below I have posted the modification that I have done. You need to add just the last two lines to the existing configuration, push the existing "/>" tag to the end.
<Connector port="8080" protocol="HTTP/1.1"
connectionTimeout="20000"
redirectPort="8443" URIEncoding="UTF-8" maxHttpHeaderSize="16192"
compression="1400"
compressableMimeType="text/html,text/xml,text/plain,text/css,application/javascript,application/json,text/javascript"/>
Note: I edited the code on 18 Feb 2012 to remove a typo.