There are three main ingredients to what you see on your screen when working in SolidWorks:
The first word, tessellation is simply a pattern of shapes that fit perfectly together. For SolidWorks and most other 3D CAD systems these shapes are triangles. SolidWorks breaks the surface of your model into bunches of triangles, a cube would have 12 triangles, 2 for each square side. The more faces the more triangles, and once you put in a rounded or curved surface the amount of triangles skyrockets.
This simple mesh doesn’t really impact performance that much but it does have a large impact on the file size. The 3D latticework is saved into the part allowing it to be viewed in QuickView mode or eDrawings without actually loading and rebuilding the model. A good way to minimize this overhead when transferring or storing files is to suppress more complex features. Another trick is to create a large rectangular extrusion that encases the entire model; this takes you from thousands of triangles to store inside the file to just 12. This eliminates the ability to view these models without loading them into SolidWorks but is a great tip for communication between full SolidWorks users.
The second point OpenGL does have a huge effect on performance. This is the Open Graphic Library, which is the programming interface SolidWorks uses to produce the pictures you see on your screen. The work station cards of the Nvidia Quadro family or the AMD FirePro family of cards both have good OpenGL compatibility with SolidWorks. What does that mean to you? Well on the basic side you have more stability. Poor OpenGL performance can cause things to disappear, ghost images to be left behind, and in the worst case scenarios screen freezes, system lock ups or even crashing.
Also the quality of the image can be improved with an upgrade to your graphics card. How straight are the lines? How round are the curves? Inadequate hardware can leave your angular lines stepped (aliased) or you curves faceted. The quality of you working experience can be affected too. As there becomes more information to display a problematic card can start to give you wait times, on zoom or pan, and choppy rotation. Of course there are settings in SolidWorks you can tweak to minimize these issues. The best approach however is to have simplified configurations with the more difficult geometry suppressed. Yet as hardware has improved we all have become more and more spoiled on seeing all the detail all the time.
The final piece of the puzzle is Rendering, the most basic rendering is simply shading the tessellated geometry and putting in shadows. With the Quadro and the FirePro cards (as well as others) there is another type of rendering you can employ called RealView. This allows for more sophisticated real time rendering giving you textures and reflections. These don’t help you design any better or faster, but they do give realistic graphics that can help when presenting an idea or taking screen captures, etc.
Photorealistic rendering is the next step up but this relies on your processor to create vivid, life like renderings for marketing and illustrations. But that is an entirely different subject…