I copied my entire music, video and epub library from my external harddrive (NTFS) to a folder in my home directory (ext4)
It was a total of about 100 Gigabytes.
I noticed that over time, the copying rate slowed.
When I did this in reverse prior to installing the new Ubuntu, the rate slowed down to 3.7 Mb per second.
In both situations, after the copying finished, which took a few hours, all functions of the computer were laggy. Windows lagged in loading up. Menus lagged when clicking on them.
The CPU graph in my indicator applet was extremely high. After reboot, it all returned to normal.
Is there some memory leak occurring when writing or reading the hard disk? What's going on here?