Freeciv runs very slow

My first piece of advice would be to go into the video options and enable Multicore Processing. It's been my experience that this is disabled by default, and enabling it usually results in a performance boost. Despite being in the video settings, this is actually a CPU option.

My second piece of advice would be to make sure you have recent nVidia drivers installed.

Note: My system is a Core 2 Quad 6600 with an nVidia GT240 512MB GDDR5, so yours should outperform mine in anything that's not using a lot of CPU cores.

You could try and tune javaw. To begin with i assume you run it like this :

C:\jdk6\bin\javaw.exe -jar "C:\jedit\jedit.jar"

To add parameters for tuning, it should then look like this :

C:\jdk6\bin\javaw.exe -Xmx256m -Xms256m -jar "C:\jedit\jedit.jar"

The above example allocates 256 MB heap memory for Java.

Further examples can be found in the Java Tuning White Paper.

Good luck :)