Bring back the recent topics box. From a user POV it is a very bad thing to remove useful things. That was the feature I was using the most on the main page. IMHO, the poll box is pretty useless (okay i know the recent topics box is more important on the load).
Remove the feature by default, but make is possible to add it back in the options menu. Most people will leave it removed anyways.
At least, make it possible for paid users to use it.
I'm a unix sysadmin of a very busy server farms. I don't know anything about your servers setup but I'm sure you could optimize a lot of other things that can make a huge difference in performance. I guess I could also be completely offtrack and all this stuff could be completely useless for you.
-Stop all those useless services and daemons to free the ram and cpus
-optimize those hard disks parameters
-load the strict minimum of modules into your kernel
-analyse the sql requests and see what are the most frequent and long requests. See if you can optimize them, or add indexes. Things that don't change often like the recent reviews box, generate the content in a static file and just include it in the main page. when there's a new reviews added, just regenerate the file. (that's where you have to look up the most)
-Tweak with those filesystems options to make it faster.
-Depending of what you use as your database server and of your setup, you may be able to spit on different disks the busiest tables (faster disk reading since it's split on more disks, you can use symlinks with if you use mysql))
-tweak with those databases parameters to make it faster (cache and buffer size)
-add more RAM if you can't free enough in the previous steps,
-check your server swap performance
-check those cron jobs and make sure the big jobs are run on the less busy time.
-'vmstat', 'top' and etc. are your friends
You also could have done all this, if yes, then you might have too small servers for the kind of services you are giving. But I'd bet that some optimization could be done.
If you really want to decrease the load , you could unplug the network cables too.
just my 2 cents
