Another performance tip if using Apache and you have access to the Apache Config files -
Put the main .htaccess info into the Apache config files.
Depending on which version of Apache this can be done in httpd.conf as a Directory
<Directory "install-directoy of Silvertripe">
Silverstripe htaccess content goes here
This is an improvement in Apache as the htaccess is now in memory and not being read each time a page is accessed.
It makes Silverstripe run that wee bit quicker.