what Guest VM OS uses the least RAM. What browser uses the least RAM

What guest OS and browser uses the least amount of ram? I like to dedicate one guest vm for random browsing and for watching instructional youtube videos.

XP?

You can get some minimal version of linux running on 100-200mb

there may be others with lower foot prints, but Minix is in with a shot at low resource use. Something like QNX for embedded systems may be lower.

http://freesoftwaremagazine.com/articles/minix/

MINIX 3 runs on 386, 486, or Pentiums or compatible CPUs, and can be installed on a system with as little as 50MB of disk space and 8MB of ram

I think my problem is my preferred browser is chrome and firefox with a zillion tabs and each tab seems to suck up RAM. My macbook seems to run my vmware vm better given the same allocated cpu and ram than my thinkpad.

Holden, that might be a woefully under stated comparison. what is the hardware in your thinkpad, and what is the hardware in your macbook? Is virtualization support turned on on your thinkpad? So many options to tinker with to help and you're throwing out the mac is better than the thinkpad at hosting vmware. Ok YOUR'S is but we know nothing as to give you info on why.... not that you care any longer.

I know this vm pretty well as I have the same vm since 2008 just moved around, it's been run on a thinkpad t61, t420, w520, w530, w540, and now a p50 with 48gb ram. Basically just moved around. It's been on a macbook retina 2011, 2012, late 2013, and 2015. Vmware fusion on osx sierra seems to require less than on a win7, 8.1 or 10 host machince with workstation. Mostly because I have to allocate less ram simiply because I have one entertainment vm and 4 work vms I have to fit on the machine at the same time. This is no problem on my newer thinkpads all with 32gb or more ram. The macbook maxes out at 16gb so I have to allocate abot 1/2 the vm ram. I can't say I've done some great detailed study but fusion running the same vm doesn't require as much ram as workstation.