Luctins's questions

I'm having some problems where GNOME Shell freezes because of a application (usually Firefox or discordapp).

Does decreasing its nice value to something around -1 prevent freezing even when under high load from some application?

My main goal is raising the desktop responsiveness under load.

System info:

lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 18.04.4 LTS
Release:    18.04
Codename:   bionic

hardware: https://www.asus.com/Laptops/ASUS-VivoBook-15-X510UR/specifications/ + a 250 GB M.2 SSD

extensions:

ls  .local/share/gnome-shell/extensions/
alternate-tab@gnome-shell-extensions.gcampax.github.com
batterypercentageandtime@copong.gmail.com
caffeine@patapon.info
clipboard-indicator@tudmotu.com
cpufreq@konkor
dim-on-battery@nailfarmer.nailfarmer.com
drive-menu@gnome-shell-extensions.gcampax.github.com
extendedgestures@mpiannucci.github.com
extensions@abteil.org
extensions-sync@elhan.io
gsconnect@andyholmes.github.io
impatience@gfxmonk.net
night-light-slider.timur@linux.com
panel-osd@berend.de.schouwer.gmail.com
screenshotlocations.timur@linux.com
ShellTile@emasab.it
sound-output-device-chooser@kgshank.net
transparentosd@ipaq3870
user-theme@gnome-shell-extensions.gcampax.github.com
web_search_from_clipboard@awamper.gmail.com
wikipedia_search_provider@awamper.gmail.com
workspaces-to-dock@passingthru67.gmail.com

also may be of note that I have no swap.

I was Looking into a Random reboot problem (probably bad cooling), and stumbled into this:

luctins@lucas-PC:~$ last reboot
reboot   system boot  4.8.0-39-generic Wed Mar  1 21:19   still running
reboot   system boot  4.8.0-39-generic Wed Mar  1 16:44   still running

wtmp begins Wed Mar  1 16:44:10 2017

Does this means i'm running two OS's at the same time? On Ubuntu 16.02