When you extrude a default, 24-sided circle with the Push/Pull tool, you create a cylinder with 26 faces. Choosing View > Hidden Geometry shows the smoothed edges between the faces:
Using two default arcs and the Follow Me tool to create an fancy bullnose along the perimeter of a rectangular countertop yields no fewer than 90 new faces:
Modeling a simple bike rack using a combination of 24-sided circles, 12-sided arcs and Follow Me, then placing ten of those bike racks in your design, adds more than 86,000 entities (faces and edges) to your model. Oof.
To dramatically reduce the amount of geometry in your models, change the number of sides in your circles and arcs before you extrude them into 3D shapes. It’s easy:
1) Create a circle or an arc using the appropriate tool.
2) Before doing anything else, type “6s” and hit Enter.
This tells SketchUp to draw the curve you just created using six sides. The “s” tells it that you’re changing the side-count and not the radius. Of course, you don’t have to choose six sides — you can type in any number you like.
Note: Once you’ve manually changed the number of sides in a circle or an arc, every subsequent circle or arc you draw will have that same number of sides.
I modeled the bike rack below using 5-sided circles and 6-sided arcs. It only has 322 faces -- an 89% reduction over the bike rack I modeled using curves with the default number of sides.
When it’s used as context in my model, can you tell the difference between the “high-poly” (geometrically heavy) and low-poly versions? I thought not.