在没有剪贴板的工作簿之间复制/粘贴变量数据集

I've been trying to optimize some of my coding and managed to cut and speed it up a lot. However there are some things that are still quite clunky (and me still a noob). Backstory is that my code is opening source and target files, copies a lot of data of variable length, closes source and then does a lot of operations and finally saves target file. I've been trying to optimize some of my coding