Yes, of course. Ligthmaps with higher resolution take more videomemory and rendering performance than lower ones and when you have a map without lightmaps you get a better performance than all the other possibilities I mentioned above.

So, for testing purposes use no lightmaps or lower lightmaps. The final map should consist of high res lightmaps. But dont forget! Overall performance is most affected by code and the amount of triangles and that stuff. Lightmaps do have a lower priority in this case.