Is this memory usage normal in Ghost? 512Mb Droplet

I run codetuts.tech in a 512 Mb droplet with Ubuntu 14, I installed it via the one-click installation process and recently updated Ghost to the latest version (0.9 I think).

When I keep logging into my SSH I see that the memory used is around 45% and that I’ve used around 15% of my 20 GB. I already ran the top command and when the Ghost process casually pops out I see it consumes around 0.4% and 9% (when I go to the ghost admin panel) of CPU and around 30% of “%MEM”.

A couple of hours ago my droplet spiked to 130% with 20 active users I got from StumbleUpon, not sure if that caused the spike because it handled the 20 users well for like 30 minutes until it spiked and couldn’t log in via SSH and had to turn it off and on again from the DO droplet panel (hard reset).

This is the data I just took with 1 active user (me):

Welcome to Ubuntu 14.04.3 LTS (GNU/Linux 3.13.0-71-generic x86_64)

 * Documentation:  https://help.ubuntu.com/

  System information as of Mon Aug  1 23:38:43 EDT 2016

  System load:  0.0                Processes:           84
  Usage of /:   14.0% of 19.56GB   Users logged in:     1
  Memory usage: 45%                IP address for eth0: 104.236.83.14
  Swap usage:   0%

  Graph this data and manage this system at:
    https://landscape.canonical.com/

113 packages can be updated.
67 updates are security updates.

New release '16.04.1 LTS' available.
Run 'do-release-upgrade' to upgrade to it.

No mail.
Last login: Mon Aug  1 23:38:44 2016 from xx.xxx-xxx-xxx.bestel.com.mx

Is that 45% memory usage normal? Should I add SWAP (I actually added a 2gb swapfile before because I couldn’t install the npm dependencies [process killed] before and removed it afterward) file or migrate to a brand new 512 Mb droplet? It runs with Nginx and I have nothing else installed, just ghost and Nginx. Should I update Ubuntu? I also got a terminal mail that the DB was blocked (though it may not be related).