Another way to look at it:
For any tip speed ratio, the blade is traveling through the air at some velocity. If the TSR is 1, then the velocity of the blade is equal to the wind speed, whatever the wind speed.
For a wind speed of, say 20 mph, then the blade is traveling around the center at 20 mph.
If the radius of the VAWT is 3 feet, then it goes around once in 3 seconds. 20 RPM.
If the radius is 6 feet, then it takes 6 seconds to go around. 10 RPM.
The bigger VAWT has a bigger swept area, collects 2x more power. So even going slower, it can develop more torque.