XenForo is also lighter weight and more modern, and I'd imagine not table based like MyBB 1.8, so pages will probably load quicker - which Google assigns some value to.
They may also have a better host/better server performance.
(2015-04-15, 08:21 PM)Dan_HiHosting Wrote: [ -> ]XenForo is also lighter weight and more modern, and I'd imagine not table based like MyBB 1.8, so pages will probably load quicker - which Google assigns some value to.
They may also have a better host/better server performance.
Not sure if I'd really call them lighter weight. Don't get me wrong - they're modern, but have never really struck me as lighter.
Tables shouldn't be used for aligning content, true, but I still doubt that that's the primary issue. It sounds like OP needs to wait for a Google Pagerank tick again, since it doesn't update instantaneously.
Your last point is very possible though.
Also, as of recently, Google will start valuing/prioritizing sites with HTTPS compatibility. @OP - You can pick up an SSL cert and that may help you a decent amount the next time Google does their major tick (probably coming up relatively soon).