i'll have to eat some crow here.
Bella was right in many respects, that InnoDB helps with speed.
I still stand by the fact that more RAM can never hurt, however.
From what I've just tested, there are 2 tables that will show an immediate increase in speed, if you convert to InnoDB
ubbt_FORUM_LAST_VISIT and ubbt_USER_DATA
it doesn't hurt to convert the other USER tables too, but they don't have constant r/w access like the 1st two.
given what Bella did and what I've now seen in terms of load/speed impact, we'll be transitioning to InnoDB for many tables where it will help.
Going to InnoDB exclusively probably won't happen til mysql 5.6, where FULLTEXT is addressed ( think search done right, finally )
So, kudos to Bella for blazing the trail and literally doing bleeding edge stuff
You deserve to be commended.
I will be posting on my blog a lot of the geek stuff that is additional ( my.cnf stuff ) to make it even better.
Most of that info came from Tom Walsh @
Express Hosting ( highly recommended!! )
If you want hosting done right for your forum(s), Express Hosting is the place to go...
He / They, now their stuff when it comes to cPanel / WHM servers and Linux in general.
</end eating crow mode>