The ultrafast gain dynamics in an electrically pumped InAs/InGaAs/GaAs quantum-dot amplifier are measured at room temperature with femtosecond resolution, and compared with results on an InGaAsP bulk amplifier. The role of spectral hole burning and carrier heating in the recovery of the gain compression is investigated. Reduced carrier heating for both gain and refractive index dynamics of the quantum-dot device is found, which is a promising prerequisite for high-speed applications.