Fork on Xen is extremely slow (Redis documentation)

Linux beefy VM on VMware:

    6.0GB RSS forked in 77 milliseconds
    (12.8 milliseconds per GB).

Linux running on physical machine (Unknown HW):

    6.1GB RSS forked in 80 milliseconds
    (13.1 milliseconds per GB)

Linux running on physical machine (Xeon @ 2.27Ghz):

    0.9GB RSS forked into 62 milliseconds
    (9 milliseconds per GB).

Linux VM on EC2 (Xen):

    6.1GB RSS forked in 1460 milliseconds
    (239.3 milliseconds per GB).

Linux VM on Linode (Xen):

    0.9GBRSS forked into 382 millisecodns
    (424 milliseconds per GB).