I would recommend reviewing your code and optimizing dodgy html and photos. If you have complex server script that slows down response time - Use some kind of server side caching engine to speed it up.
your site is on the hosting space or install a server ? if your site installed on the server, can use cache server. If you are using hosting space, can try to write some cache files by using php,still not improve too much, contact your hosting space support.
enable gzip compression, combine css, js, serve static content from a non cacheable domain, optimize images (same image may be larger as png than jpg and reverse). Maybe you shoud consider to use a tool like PageSpeed plugin (for firebug);