Disable Search Indexing in options. It uses a buggy piece of garbage called Akonadi in the background and was causing one core of my CPU to stay at 100% for no reason.
Baloo is the file indexer for KDE. It has little or nothing to do with Akonadi.
Akonadi also hogs a lot of memory for services i never use (calendar and centralised mail service, not sure if thunderbirs uses them). It’s not a problem for my desktop pc so i don’t tinker with it, on my 8 year old laptop on the other hand I’m going to have to switch to something lighter in the future (lxqt or xfce).
I’d love it if the KDE devs made Baloo and Akonadi optional. Their insistence on including them reminds me of Micro$oft’s insistence on bundling Internet Explorer and integrating it into the OS shell in Windows 98.