I had tried many forum software and i have a big board too around 1000k post which is run by an another forum script. But it brings me more load.
Finally i moved to Mybb , i loved its plugin system and it is faster than all script.
So i love mybb as it is ease to mod and use.
mybb 10/10
give your feedback and say why you love mybb
Simply, it's the best free product out there.
It has it's issues, but it's still much better then any of the others.
Its because i don't have any reason to hate it.
I hate phpBB for its complexity, SMF for its bad development cycle, VB as it doesn't have consistency and is bloated, and so. MyBB is the only software that has nothing to hate.
There is so very much possibility one could do with MyBB. Its varied plugin system allows to develop very amusing plugins. And one could modify the MyBB to the extent he wants, for example, there are so many forums that are modded so hard that you're likely to believe its MyBB but other software, such as Mebes and some other heavily customized. No reason to hate, because there are lots of reasons to love.
I love MyBB because administering the backend of the forum is fairly easy compared to other forum softwares.
Because its updates and bug fixes are quite regular.