The pressure on the pedals depends entirely upon the gear ratio you've got and the size of the sprocket attached to the hub. The gear ratios are usually published for different hubs. If you want a higher top gear, your best bet would be to increase the size of your chainring up front or decrease the size of the cog in back.
That said, it's very possible that you are a grinder. It is not good for your knees to pedal around in the highest gear at all times. Try to keep your cadence (speed of your feet on the pedals) at least 60 rpm at all times and ideally around 90 rpm while cruising. Your knees will thank you for it in the long run.