Cloud storage is an essential matter for people's organization and growth. Unfortunately, it is too risky if the data and files are hosted only on a single cloud storage provider. Meanwhile, a possibility exists for insider attack to steal or corrupt the data. Using multi-cloud storage providers and distributing the data over is a possible solution to improve data security in such a context. However, the performance of uploading speed of a cloud server provider plays an influential role. In this study, we used multi-cloud storage with the optimization parameters to speed up the uploading time spent to store data in several cloud storage services. Slicing the data and sending the contrasting amount of data over multi-cloud storage according to the optimization result can provide better security features and upload faster. This work considers the upload time and access latency parameter to implement the optimization model. Our finding shows a 12% enhancement in distribution performance compared to traditional data slicing without optimization, if equally sized slices are sent over multi-cloud storage. In future work, the effectiveness of bandwidth should be included, especially on the optimization parameters.