Yes, Monotonic is right, DGDK is capped at my refresh rate. I've installed everything I need to install, everything is as it should be, I compiled in release mode, even tried tweaking a few build settings in favour of 'fast code' for x86, still no luck, to be honest, I really don't know what the problem is.
I have an old system (P4, 2.8Ghz, 1.3GB RAM, GeForce2 64MB MX 400), I suppose I should really get a better graphics card, but I get about 325 FPS using TrueVision 6.5, so I don't think I should be getting 70 FPS with DGDK.