The dev team of software.o.o found the bug and in the mean time did a "hot fix" for this to let software.o.o run smoothly again.
More information here:
https://github.com/openSUSE/software-o-o/pull/359
We are facing trouble with the performance of software.o.o atm - we are investigating this issue and inform you here if it's solved.
Thanks to everybody for reporting this.
