You can move just about any file to a USB storage device, as long as the file will fit on the device. The game is smaller than many modern computer programs, though, so I wouldn't think the file size is affecting the computer's performance (unless it has a very tiny hard drive). If you quit VV5 each time you're done playing, and the computer is still slowing down, there is some other reason for the computer's slowing down.

Our games are designed to be installed and run from a computer's primary hard drive. If you want to run the game from a USB device, you should get assistance from a friend or parent who is familiar with setting up a program to run from a USB device.

could you tell your computer's specs? if c-drive doesn't have much space left then computer is slow.

i used about 1/4 of the c drive

if comp has low memory it uses hard drive to to store things on memory and if hd is bit full then operating system does alot transferring between hd and memory which slows down computer.

But only when the game is running... Unless the hard drive is very full and it is affecting the swap file the fact that the game is installed but not running wouldn't make any difference. Computer hard disks are much larger than they used to be a short while ago, and the size of VV5 is not really that large by modern standards.