vBulletin Performance Optimization

I have been dealing with vBulletin for almost a year now. I manage a vBulletin installation for my friend at Fashionese Daily forum. Anyway, Fashionese Daily forum have used other forum/discusion engines like punBB and MyBB. It’s now using vBulletin 3.7.3 Patch Level 1.
It’s a pretty busy-traffic forum anyway. In average, there are 1,000 new posts everyday. According to forum stats, there are 500 – 600 online users during the prime ours (registered and guests). From the very beginning, I try to maintain its performance so that the forum is available.
Based on many articles about vBulletin optimization, here are what I did:

MyBB Goes Open Source

MyBB forum software just published an announcement about its new licensing software. It’s now distributed and licensed under the popular open-source GNU GPL v3. According to the management, this decision was made because they want to open MyBB up to the community and help support the world of free software. Read more details about this new license.
I do not use it right now, but I helped my friend at Fashionese Daily using it few months ago. We switched from punBB to MyBB almost without problems and MyBB helped the community grew (Read the whole story, in Bahasa Indonesia).