Ubuntu based problem when copying heavy files and folders

Ubuntu, Linux Mint (which is based on Ubuntu) and other Ubuntu based distro out there all suffered from a problem while copying heavy files and folders using GUI.
When I tried transferring my data from a External HDD to another External HDD using GUI (drag and drop, or copy and paste), it was showing high copying speed at first, but then it slowed down until the point I decided to kill it.
Doing some research online, I found out that it is a bug and it still has not get fixed although it’s been informed for awhile.
So, how do we copy heavy files and folders efficiently? Using CLI of course.
But using “cp” command will just show us what file it is copying, not how fast or percentage copied.
There is an app for that, called cv (core utils view) made by Xfennec. Xfennec just changed the name from ‘cv’ to ‘progress’ (maybe for better recognition). You can download it from here: https://github.com/Xfennec/progress
Install dependency and build it:

cd progress
sudo apt-get install libncurses5-dev
make && sudo make install

How to use it?
Using ‘cp’ command as usual.
In another terminal instance, issue this to get information about cp command (progress, speed, ETA…)

watch progress -qw

That’s it.