Hope this helps some of you…
Make sure you configure (optimize) your Swap Memory - I suggest 1GB for your 1GB RAM VPS.
And improve some settings, especially I recommend improving these parameters to the values below.
vm.swappiness=10
vm.vfs_cache_pressure = 50
In order to set it, and make it persistent for restarts, see the tutorial at
https://www.digitalocean.com/community/tutorials/how-to-add-swap-space-on-ubuntu-16-04 (English)
(this is specialized for Ubuntu)
Debian Info e.g. here https://debian-blog.org/linux-swappiness/ (German)