Multiplayer lag

[Moore282]

Ok, I know that noob questions can get annoying on forums, but I've been searching for weeks for answers to my lag problems with no success. I'm begging for help, just tell me what I need to do to my computer to play lag free. I'd like to compete in some race series' online eventually. My goal is to have the graphic settings pretty high and no lag. Please let me know what I need to do or buy to achieve this.
My problem:
When I'm playing multiplayer with more than about 10 riders on the server it lags and I don't like it. With less than about ten riders all is well with no lag.
First I thought it might be a graphics problem... but I have no idea about graphics cards etc...
So, I found some posts by JLV saying to update drivers and disable Catalyst AI. So, I did that as well as turned down all the graphics settings in the game to about half and this is what i came up with..


Idk if this is good enough..let me know of anything I can do to as far as graphics go to improve game play.

Next I downloaded Fraps to take videos of the game. When I use it it lags just as bad as when I'm playing multiplayer with more than ten people on the server. So I got to thinkin that the problem might be that I don't have enough RAM or something like that. As I said, I don't know much about computers, so I cleaned up my hardrive and deleted as much stuff as I could and this is what I came up with..

Let me know if this is enough memory, speed, whatever and if not, please let me know what I can buy to improve game play.
Also, I don't think it is my internet connection. The speed is 75.0 Mbps, I'm not sure if that is fast of not.
If this isn't enough info let me know I will post anything you need.
Videos of lag..

Single player with lag from fraps?
Single player with lag from fraps?
Multiplayer lag+fraps lag=double lag

Videos are unlisted to not give mxsim a bad name or anything
Thanks,
Sam

[Moore282]

The second video listed "Single player lag from fraps?" is a little less lag than the lag I get from playing multiplayer with more than ten on the server (with no programs running on my computer other than mxs), but its a good illustration of what I'm experiencing. Any help is much appriciated.
Thanks,
Sam

[jlv]

Try setting the roost to 0.