Frame rate issues with lighting.

Hello, and I apologize for this long description. Bear with me. I am having some problems with frame rates especially when adding any lighting. I am now in the updated 5.5 version.

I have many low poly objects in scene and everything moves fine but then again everything is too dark even with the "daylight settings" which if you turn all the way up makes the ground blinding but still leaves buildings dark. So I tried to self illum the buildings and turned the texture tone down. Wit a bit of adjustments I made things visible but then it messes up the shadow effects.

So finally I started adding things like point light and spot light. The results were much better but as soon as i turned on visible lighting n viewer I could not even move the scene viewer camera even before using preview Game hitting play or doing the other of build & run.

The result was Unity crashed and my computer froze for a few minutes as Unity's background processes finally stopped. When I fired Unity back up it had the same lag so I had to fight with removing all the point and spit lights and the lag reduced significantly.

SO I tried one more thing.

I added three directional lights to light up areas at the different angles to the default directional light. I turned shadows off in these added three. The outside of buildings and anything in the scene then are lit up much better and I turned the turned the intensity of these three down so as to not create the blinding effect. It lags again but doesn't crash anything but it does nothing for character inside a building.

The interiors are self illuminated so you can see inside (IE inside a shop you walk into) but the characters and objects still appear dark.

I am of course getting frustrated.

If there is a tutorial for this current to Unity 5.5 (Not earlier) it would be much appreciated.