Does /dev/random in virtual guests provide good random data?

[Yuri]

'cat /dev/random' in Linux VM (tried Ubuntu and Arch) is extremely slow, 
supposedly because VM runs out of entropy. This cat sometimes stops for 
minutes, and usually produces very few bytes per minute. Randomly 
clicking on the window helps speed it up a bit.

Same in FreeBSD VM produces steady ~28MB/s stream.

Does FreeBSD VM do something special for entropy, or the resulting 
stream actually lacks entropy, or maybe Linux does something wrong? I 
ran VMs on the same FreeBSD VirtualBox host.

Somewhat relevant link: 
https://stackoverflow.com/questions/26021181/not-enough-entropy-to-support-dev-random-in-docker-containers-running-in-boot2d

Yuri