The first question is, which
RenderingPath do you use? You can choose a path at
PlayerSettings|OtherSettings|RenderingPath. There are some pros and cons of each and you can read more about them and their differences, especially in performance, here.
Second important thing are your light quality settings, especially the pixel lights count. Flagging light as 'not-important' means that it could use vertex lighting instead of pixel lighting.
Since pixel lights are much more expensive than vertex lights, Unity will only render the brightest lights at per-pixel quality. The actual number of pixel lights can be set in the Quality Settings for webplayer and standalone build targets.
You can explicitly control if a light should be rendered as a vertex or pixel light using the Render Mode property. By default Unity will classify the light automatically based on how much the object is affected by the light.
You can check
RenderMode property on each light you use.
Another good place to look at is how many textures are you using on your objects, how many vertices they possess and how complicated are shared you are using. All these three factors are relevant, when it comes to use built-in
dynamic batching unity feature.
Also, you can experiment with point light instead of second directional light, the point light could be also attached to the camera. Can't say anything better without more knowledge of your specific case, hope that these information will give you any help.