Tokamaks need the central solenoid to have a current ramp, so at some point you run out of voltage. You can turn that way down, but you get less plasma performance. You're traditionally limited by heat rejection capabilities of the vacuum vessel.

These are science machines to learn about plasma and increase performance of future machines. A real reactor involves a lot of engineering to handle the heat rejection problem (and turn it into a revenue stream if you're clever). In terms of the pulsed nature: not really a problem if you keep the duty cycle high enough and maintain sufficient buffers in your coolant to keep the turbines happily turning away.