Baloo file indexing
Baloo is a file indexing service and KDE Plasma Workspace will not work without it. In some cases indexing is makeing problem and consumming the whole system resourses. To ckeck the system load run 'top' in a terminal. If you find a baloo process at the top of the list you may send it a kill signal. Type 'k' in the top program.
You can disable indexing with the command:
will show you the current status.
Unfortunatly there is no way to provide system defaults.
Beginning with Ubuntu 20.04 you can use the command
to reclaim the used disk space. This can be several gigabytes.