Hosting environment/ General tips
Get a dedicated server.
Host your site in the country where your customers are.
Don’t host files on your web server that you do not use, large or small.
Goto MySQL Admin and select all the tables and repair and then optimize them.
Use a PHP accelerator like APC, ZendOptimizer+ or Xcache.
APC – http://pecl.php.net/package/APC. Increased the APC.shm.size to something like 128 to allow more data to be cached by apc.
Xcache – http://xcache.lighttpd.net/
Only install necessary Apache modules.
Enable Gzip Compression in htaccess.
Compress output, use zlib.output_compression or mod_deflate.
Use a Content Delivery Network (CDN) for parallel transfer of static content. There is a Magento extension that can help you do this with category and product images: the One Pica Image CDN.
For more info!