Note, this is a work in progress for me on the eternal search to improve how my tf2 runs. The following commands helped my game run better, but are not always stable, I crash every 2hrs or so, sometimes not at all. As you all know TF2 was not optimized for multi core, but there are ways around it.

If you want further explanations, I will give them, but right now I'll just give you the commands and how to use them effectively. Remember THIS IS FOR MULTI CORE CPUs ONLY!

Go to your "X:\Steam\SteamApps\ACCOUNTNAME\team fortress 2\tf\cfg" directory. Once there, search for a file named "autoexec.cfg". If you have one, then copy the following lines in to it and save. If you don't have one, then simply create a text file with the name "autoexec.txt", copy the following lines, save, and then rename the file to "autoexec.cfg". This file is auto executed upon starting up the game.

This is what needs to be copied:

mat_queue_mode "2"
r_threaded_renderables "1"
r_threaded_particles "1"
r_threaded_client_shadow_manager "1"
cl_threaded_bone_setup "1"
cl_threaded_client_leaf_system "1"
snd_mix_async "1"

Again, if you have questions on the specific commands, then shoot, I'll answer.

There is one other thing, if your processor is not the best, or RAM not the fastest, there is a parameter that can help you a bit, by increasing the heap size. Go to your steam games list, there select tf2>>right click>>properties>>set launch options and copy this in there "-heapsize 1048576". That makes the heap 1GB. You may change the value of course (specified in KiloBytes), but I don't recommend using a higher value than half your RAM size.

Now these don't turn your PC in to a TF2 rocket ship, so don't expect it to bring you to the next level, but they WILL help. They added a good 15 fps at the heaviest of combat scenarios for me.

I already tried the 'perfect' version of this according to some guy on the steam forums, it had like 20 command lines in it.
It still failed epically for me, no boost in fps and i crashed all the time (and yes i do have a quad core)

Yes, well not all of us bought our computers from the Pentagon's second-hand sale.

Mate if you have that good fps already on those settings dont bother with those commands because they are renowned for not working properly and generally cocking things up.

Does anyone know if updating my motherboard bios will help with performance?

Being a bit paranoid, I probably wouldn't update unless you know your bios is broken. Graphics card & cpu is what it's all about

I run 50-100 FPS on 1280*1024 (which is all my little monitor can handle ) But I might give this a go, to see if I can raise the 50 to 60.

^^ Dont start chaos talking about his computer