In this work, structural changes at high heating rates of Fe74Mo4P10C7.5B2.5Si2 metallic glass were studied using high energy synchrotron radiation with microsecond time resolution. Amorphous ribbons before and after isothermal heat treatments at different temperatures were analyzed by laboratory X-ray diffraction (XRD) and differential scanning calorimetry (DSC). In addition, Flash DSC (FDSC) measurements were performed in the laboratory to investigate the crystallization behavior at high heating rates. This study investigates heating rates from 0.08 K/s to 10000 K/s, covering five orders of magnitude. Thermal cycling at high heating rates showed a broadening of the supercooled liquid region and a decreased activation energy of crystallization. Employing high-energy synchrotron radiation during FDSC measurements and comparing it to laboratory XRD isothermal heat-treated samples show different crystallization behavior due to the formation of metastable phases like γ-Fe, which is retained at room temperature at high cooling rates.