Faster Wheels & Tyres for my Cyclocross bike
Its not the size of the tyre, its the knobliness and the rolling resistance.

Assuming 35 is the tyre size then you have a 15-24 mm rim, based on this DT Swiss PDF  and maybe could go as far as a 20mm tyre.  This is rim width dependant though.

Realistically, a smooth 28-25 mm tyre will give you a more comfortable ride than a narrow tyre, and will roll just as fast if not faster.

CX bikes are fine for commuting - a road bike might be slightly faster but often takes away things like fender/mudguard mounts, or rack mounts which add to the overall comfort of your ride.