Problem resolved i have sorted tmpfs files to check what uses most space:
du -h /run/user/1000 | sort -h
this was opera so i have removed it:
rm -rf /run/user/1000/psd/unx-opera/Service\ Worker/CacheStorage/*
This have cleared over 900MB and i can run all apps without any problems.
tmpfs should be cleared at system reboot, not sure why this stay at constant 100% of usage.
I have changed size of tmpfs, by default it is 10% from total RAM installed:
sudo nano /etc/systemd/logind.conf
uncommented and changed entry:
RuntimeDirectorySize=10%
to
RuntimeDirectorySize=8G
then
sudo systemctl restart systemd-logind
I`ll start to worry if sytstem will eat whole 8GB, if not… happy days.
Thanks for everyone for help.