Well you should not expect magic from vbseo,
if you really wanna succeed you should have below options at the same time :
1. An Optimized server : A fast server with proper optimizations ... always try to check your website's performance here : www.webpagetest.com , most of the items here are server related.
2.Proper vBSEO settings
3.focusing on the main pages of your website which are Threads and Forums,
always try to do keep these pages clean for guests , remove all unnecessary sections and put the H1 and below description (I use vbseo relevant replacements for this issue) tags as top as possible in your pages, and also use other heading tags in your thread pages in proper areas.
4.CDNs will really help you to improve your website's performance.
5.always add unique content to your website (unique content = contents that (almost) no one else has)
6.Always try to check your design's validation.
I am sure if you do these items you will see great results in some months.
To be honest optimizing the vb is not an easy task but I have done it and I have got great results from it.
Please feel free to ask any question regarding above suggestions.