That is an archived thread from 2013, here is the text from it:
A small VM. It boots in 1-2 seconds.
Based on the awesome Tiny Core Linux.
Source: http://www.tinycorelinux.net/welcome.html
What I did is only:
- install it to a disk so you don't need the ISO.
- create a VM with 48 MB of vRAM. It only needs 41 MB actually.
- I keep the vDisk at 1 GB just in case you need to add more things. Because of thin provisioning, only 40 MB is used.
- package it into OVA format
While I posted another VM, which is smaller in Disk foot print, I'd recommend you use this one. I've run both for 1+ week and VC Ops show that this one takes a LOT less CPU cycle. This one takes around 4 MHz. Takes us back to the good old days of 8086.... 
Hope you find it useful. Credit belongs to the smart folks at http://www.tinycorelinux.net/welcome.html