OK that one made me lol, thx 
How do I debug my Pi-hole installation? is on top of my Pi-hole bookmarks now.
Resetting the database will do absolutely nothing regarding the load situation. It seems like "load" is the only trail we're following currently.
There's load, I know where it comes from, I have long-term records, I'm aware of and using tools like htop, iotop -aoP, bcmstat (Pi-specific), glances etc. - I just can't compare load to "database is locked" situations. No pattern (yet), not even a single match. Therefore atop might be of interest. But as it can take months for the next locked database situation (or even 3 years in case I would start from scratch) with several reboots in between.