Here are a couple of ideas...
1. Disable any modules are not using. On the Sitefinity backend go to Administration > Modules & Services. Not sure when this feature was added to Sitefinity.
2. Upgrade to the latest version of Sitefinity. You no longer have to upgrade sequentially to the latest version. Telerik now supports users upgrading the latest bits. I highly suggest this because the latest version of Sitefinity has really improved the load times dramatically. Here are some details around the upgrading... http://docs.sitefinity.com/best-practices-upgrade
3. Check out the client-side and server-side optimization best practices. Just go to the following URL and watch the videos. http://docs.sitefinity.com/best-practices
Hope you find this useful.