Why Lubuntu 20.04 is running slow when I use Opera or LibreOffice

Solution 1:

swap

You have no swap. This is what's causing your slow downs and freezes.

free -h

             total        occupied        free      total  buf./time.   available
Memory       2,8Gi       1,7Gi       160Mi       198Mi       956Mi       718Mi
Swap:          0B          0B          0B

Let's create a 4G /swapfile.

Note: Incorrect use of the dd command can cause data loss. Suggest copy/paste.

sudo swapoff -a           # turn off swap
sudo rm -i /swapfile      # remove old /swapfile

sudo dd if=/dev/zero of=/swapfile bs=1M count=4096

sudo chmod 600 /swapfile  # set proper file protections
sudo mkswap /swapfile     # init /swapfile
sudo swapon /swapfile     # turn on swap
free -h                   # confirm 3G RAM and 4G swap

Edit /etc/fstab.

sudo -H gedit /etc/fstab

Confirm/add this line in /etc/fstab... and confirm no other “swap” lines...

/swapfile    none    swap    sw      0   0

reboot                    # reboot and verify operation