Container virtualization is emerging in cloud computing due to its lightweight feature. Container live migration is the basis for many cloud management capabilities, which migrates a running container to another physical node with minimal downtime. Performance is the focus of container live migration research, but through a detailed analysis of existing container live migration systems, this study finds that there are still some problems affecting the performance, including low parallelism of dump, non-convergence of pre-copy policy, and low parallelism of root file system and running state migration. To solve these problems, this study proposes and designs three optimization strategies or algorithms including the resource awareness-based parallel dump mechanism, post-copy policy-based running state migration, and multi-priority-based parallel transfer scheduling algorithm. In addition, the paper realizes a high-performance container live migration system, namely, Dmigrate, based on Docker. Experimental results show that compared with the latest research, Dmigrate can effectively reduce downtime by 17.05%, and the total migration time is decreased by 24.33% on average.