Crystallization kinetics in thin films of Ge<sub>2</sub>Sb<sub>2</sub>Te<sub>5</sub> doped by Bi and Ti was studied. It has been shown that introduction of these impurities may have an impact on the kinetic parameters of the crystallization process. The possible recording and storage times of devices based on investigated materials were evaluated. It was shown that GST225 + 0,5 wt. % Bi has the best characteristics among the studied materials. Estimations showed that this composition can provide switching time of the phase-change memory cells less than 1 ns and it is extremely stable at room temperatures which is important for the reliable storage of information in memory cells.