Odd, you shouldn't have any problems. When I was on Daryna (Mint 4) I had no problems. Check if there's any other processes running perhaps? System Monitor in administration menu.
Linux Mint 8 RC1 = Nice
'apt install' can be used on Linux Mint as a shortcut for 'sudo apt-get install'. 'apt x' can be used for various other apt commands as well.
When a problem is solved, please add [SOLVED] to your thread title.