Hi guys, I’ve been looking through the install docs and catch a divergence in the first one about vagrant’s default memory:
The discourse-as-your-first-rails-app states in step 1 - 3: The VM image we set up defaults to 1 GB of memory…
Increase the VM memory. The VM image we set up defaults to 1 GB of memory, which makes it friendly to run on 4 GB machines. But this is the practical minimum — performance will be a lot better if you can ramp the VM memory up to 2 GB or even 4 GB. To do so, change your system’s DISCOURSE_VM_MEM environment variable to the desired amount of memory.
But the updated Vagrantfile has:
# This setting gives the VM 1024MB of RAM instead of the default 384.
v.customize ["modifyvm", :id, "--memory", [ENV['DISCOURSE_VM_MEM'].to_i, 2048].max]
Looks like the default now is 2Gb! Just a typo, but is good to keep the docs up to date. 
Regards