Thermal flying height control (TFC) has recently been implemented in magnetic recording disk drives to reduce the flying height at the read/write element of magnetic recording sliders. This paper investigates the flying height and response time of TFC sliders with single and dual TFC heaters and thermal insulators. Simulation results show that the presence of a thermal insulator has little effect on the response time of thermal protrusions. In addition, the effect of the dimensions of a TFC heater on the flying height and thermal response time is important. For a given heater power, the dual TFC heater design with thermal insulators can provide a very flexible control over flying height and response time of TFC sliders.