Timing side-channel attacks are an important issue for cryptographic algorithms. If the execution time of an implementation depends on secret information, an adversary may recover the latter through measuring the former. Different approaches have emerged to exploit information leakage on cryptographic implementations and to protect them against these attacks, and recent works extend the concerns to dynamic execution systems [3, 15, 24]. However, little has been said about Cross-ISA emulation and its impact on timing leakages. In this paper, we investigate the impact of dynamic binary translators in the constant-time property of known cryptographic implementations, using different Region Formation Techniques (RFTs). We show that the emulation may have a significant impact by inserting non constant-time constructions during the translation, leading to significant timing leakages in QEMU and HQEMU emulators. These leakages are then verified using a statistical approach. In order to guarantee the constant-time property, we have implemented a solution in the QEMU dynamic binary translator, mitigating the inserted timing side-channels.