Update: I have implemented a better version of this code. The new version is able to display progress separately and auto hide the rsync window after finishing copying. You can look at this post Emacs - Async File copying with Rsync - Update

Emacs Dired mode is a great alternative for the default file explorer application on MacOS, Windows or other systems. That is because Dired mode provides with the ability to quickly navigate through files and directories, mark multiple files for later operation using keyboard. However, when dealing with large and multiple files, it show one annoying drawback. When we want to copy or move a big file, Emacs will be entirely blocked until the copying/renaming process complete.

There are several methods to fix this problem. My solution is to replace copy command with rsync and execute it asynchronously so that the rsync process can execute in the background while you can still interact with Emacs normally. Moreover, rsync can also display the progress of the process (the percentage of file copied) as well as determine which files are already exist to avoid duplicated copying (since its main purpose is to sync).

Below is my solution. If you want to use it, simply copy and paste it into your .emacs and restart Emacs for changes to take effect.

Note: this piece code is only compatible with those unix-based systems because they are usually equipped with rsync application by default.

(defun tmtxt/dired-rsync (dest)
  (interactive
   ;; offer dwim target as the suggestion
   (list (expand-file-name (read-file-name "Rsync to:" (dired-dwim-target-directory)))))
  ;; store all selected files into "files" list
  (let ((files (dired-get-marked-files nil current-prefix-arg)))
	;; the rsync command
	(setq tmtxt/rsync-command "rsync -arvz --progress ")
	;; add all selected file names as arguments to the rsync command
    (dolist (file files)
	  (setq tmtxt/rsync-command
			(concat tmtxt/rsync-command
					(shell-quote-argument file)
					" ")))
	;; append the destination
	(setq tmtxt/rsync-command
		  (concat tmtxt/rsync-command
				  (shell-quote-argument dest)))
	;; run the async shell command
	(async-shell-command tmtxt/rsync-command "*rsync*")
	;; finally, switch to that window
	(other-window 1)))
;;; bind it to C-c C-r
(define-key dired-mode-map (kbd "C-c C-r") 'tmtxt/dired-rsync)

I also bound it to C-c C-r, if you want, you can change it into another key binding that you want.

After restarting Emacs, you are ready to use that new function. Open up a Dired buffer, mark some files and then C-c C-r, select the destination directory and press RET. If you have the variable dired-dwim-target set to t, you can open 2 dired windows and this command will automatically choose the directory in the other window as the default destination folder.

Screen shot from my Emacs:

Rsync process with progress.

Rsync process with progress.

Rsync process when complete.

Note: You should only use this function when you want to copy large files. For the small ones, just use the default copy command of dired because this command always open a new buffer for showing the progress.