When OpenBVE gets laggy, sometimes the controls get a little unresponsive. Its a flaw in the game itself, not your keyboard. But sometimes, however, you DO need a faster PC to play some of the newer generation routes or else it gets laggy
As for that no-objects problem you posted a screenshot of, make sure you have all the objects neccesary. You can find out what they are by clicking the Show Issues button on the error message. Sometimes you also need a certain route already installed for other routes to work.