I love your implementation Yann, im going to use that, with an added control to pause the game if the fps drops below 10, as RamPackWobble said dt will not go below 0.1 and i think there is where the problem is.
I have to read the manual about the system functions of C2, i didn't know some of those even existed.
vtrix, yeah i think most are cheating, maybe using something like cheat engine to modifiy the timers or just stop the clock.
For the next implementation i'm going to do some research on ways to prevent that, i already have a lot of security measures in place to avoid "fake" post request to the server, currently the scores and all sensitive data is encoded in AES256 before it gets send to the server and the score is "masked" behind a few maths operations.
Thanks everyone, especially Jann and RamPackWobble!
Great community support as always.