Are you having performance issues when viewing and rendering your SketchUp projects? It could be that you are using models with too high a resolution for the view you have created or that you are using high polygon count models.
When importing items from 3Dwarehouse, use the filters to remove high polygon count models from the results, so you can better optimise your scene. Foliage and plant models often suffer from this issue.
A helpful tool that you'll find in Extension Warehouse (https://extensions.sketchup.com/) is a free extension called Goldilocks...
Goldilocks is a tool for identifying where you have too much or too little Resolution in your Textures for a given viewpoint. The last part is important because if you're far away from a textured surface you need less detail than when you're really close up. Having too much resolution just increases file size with NO INCREASE ON QUALITY for rendering with LightUp or any renderer - including raytracers. Its simply a waste of space. For realtime products like LightUp where you can move anywhere you like, you might wonder whats the point. Well even though you can move "anywhere", the reality is that you'll have known places you'll be wanting to explore and Goldilocks is a handy tool for finding places where you've gone a bit nuts on Resolution. In particular, you do want to keep "Texture density" roughly constant around your model - having very blurry low resolution textures next to super crisp high resolution textures can be very off-putting.