It's not you, it is the cheap host.
http://www.webpagetest.org/result/140523_V4_S3J/
You're loading only 232 kb with 54 requests.
CPU usage at bottom of the chart here:
http://www.webpagetest.org/result/14...S3J/1/details/
Shared hosting provider is ALWAYS going to blame you. You are using Cloudflare so the host machine isn't even loaded that much to deliver the files.
The problem here is the oversold, overloaded, tired old machine your host has you on. It's not vBulletin.