you didn't mention what kind of lights you added. You didn't indicate whether you were using Global ilumination (GI). you didn't indicate which version of Light Wave you are using. need a little help in order to help
Area lights take more render time than say spotlights; Global Ilumination takes way more time than area lights.
The latest versions of Lightwave have vastly improved render times and improved rendering of Global Ilumination. However, there is much to understand on setting up Global Ilumination properly in order to get the best render times and the best renders.
Why don't you let us know a bit more about your scenes and how you've got them lit. Then we can be much more helpful
Rich :blush: