Tested also the fetch page and Google was able to grab data much better from Xenforo then Vbulletin.
Insert a random thread from Xenforo:
Got an overall PageSpeed Score of 89 (out of 100) See attachment.
Insert a random thread from Vbulletin 4.x version:
Got an overall PageSpeed Score of 66 (out of 100) see Attachment.
Edit: However, vb5 is catching up:
Insert a random thread from Vbulletin 5.x version:
Got an overall PageSpeed Score of 87 (out of 100) see Attachment.
89.5 KB Views: 49