Hey
When you say it lags, do you mean in general - like no matter what you're doing in the game? Or only when you're building tracks/laying things down?
Do you have any other software running while you're playing the game - maybe a media player (VLC/WIndows Media Player) or are you downloading in the background?
From what you posted about your PC I don't see why RCT would be lagging here. The only other things that I can think of are:
1. Overheating (I doubt this)
2. Malware
3. A version of DirectX which is lower than the required version
4. Outdated graphics card drivers.
Do you ever scan your computer for viruses/Trojans etc? If not then maybe it's worth a shot. If it picks something up then that could possibly be the cause.
Check your DirectX version and let us know what version you have, if it is below version 9, then please try and upgrade to a later version:
- To check Direct X version, click the Start button, then in the Search box just above the start button, type "dxdiag" (without the quotes), and a a window will open (if you are given a message with a Yes and No button, click No is it's not necessary))
- When the DxDiag window opens, in the middle, down the bottom you will have "System Information", the very last piece of info should tell you what version of Direct X you have installed, the latest version is 11 (I think), so remember that you need version 9 for this game to work properly.
- Click Exit once you've found which version you have.
If you have less than version 9, you can download it from here:
http://www.microsoft.com/en-au/download/...aspx?id=35
Now with the graphics card you can see if you have the latest driver by going to the amd website. They have a tool on there that auto detects your thing and tells you which driver you need:
http://support.amd.com/us/gpudownload/wi...etect.aspx