Performance problem on Dogsuniverse.dk

We recently launched http://dogsuniverse.dk and are experiencing some serious performance issues: http://www.webpagetest.org/result/121219_BG_C56/

What we already did or are currently working on:

- Installed and configured W3 Total Cache
- Database Cahcing using memcahced
- Combine and optimized .js
- Minifiy .js and CSS
- CSS optimization (working on)
- Server optimazation (on-going)

What worries us:

- Time to first byte
- Number of request
- Should we use CDN

Looking for any ideas what we should prioritize optimizing or if any of the plug-ins we are using are know to have performance issues.

Any suggestions and opinions are welcome

Torben Grue
Dogsuniverse.dk