Any UPS problems that bad should probably be reported to the relevant mod authors, to see if any optimization can be done about that, because that does seem rather high. I know Cerys specifically is made by a pretty competent dev who should be able to either resolve the UPS issues, or provide a decent explanation for them.
As for disabling them yourself, you can easily unpack and edit this mod yourself by removing the relevant lines in info.json, then give it a high version number so it doesn't get updated (make it 1.1.0 or 2.0.0, and it probably won't ever get overriden). Then restart the game, disable all mods, enable only your custom version of All Planets (and Space Age), then finally load up your save and say Yes when it asks for whatever the popup is to ignore the removed planets + dependencies