Abstract: Reverse time migration based on the two-way wave equation is a high-precision imaging method capable of handling full wavefields without being constrained by formation dip angles, thereby enabling accurate imaging of complex structures. However, the conventional strategy of storing the entire source wavefield requires repeated disk read/write operations at each time step, which not only consumes substantial storage but also introduces significant I/O latency, imposing severe constraints on computational efficiency. To address this issue, two storage strategies have been proposed to optimize the traditional imaging algorithm: one involves downsampling the source wavefield based on the Nyquist sampling theorem to reduce I/O frequency, and the other stores only the effective boundary wavefield and reconstructs the source wavefield during backpropagation. This paper systematically analyzes both optimized imaging algorithms, demonstrating that both can effectively reduce storage requirements and significantly enhance computational efficiency. Numerical examples show that the imaging accuracy of the two algorithms is basically the same. When sampling and storing the source wave field, the storage interval needs to be reasonably set, which can improve the computational efficiency while meeting the imaging requirements. However, the boundary wave field reconstruction strategy requires more GPU video memory. When using GPU to accelerate the calculation of large 3D models, the imaging algorithm needs to be reasonably selected.