Which is Light Baking approach is best for maintaining smooth continuous level loading?

My game takes place in a large city block, with a few different stores and apartments that the player can visit in which are loaded and unloaded additively.

A part from some subtle flickering of the street lamps, the lighting is fixed and I want the minimum spec to be a mid-range PC.

It seems baked GI is recommended, but how does baked GI have a different impact on level loading performance vs Realtime Global GI?

If I go with baked GI, I'm anticipating a lot of memory being reserved for the light maps, and I anticipate the frames where the level loads for the first time having to call up that memory, resulting in hitching etc. If I go with Realtime GI, it's less performant overall, but how much so?

Based on your experience, which approach would you recommend I go with for this project?

thanks!