What's the problem with n-gons?

[anicg]

There shouldn't be n-gons in your geometry, why?

Large flat surfaces (100% flat) can either be an n-gon, or hundreds of polygons. In a scene, if multiplied by the number of surfaces, by the number of models it saves on polygon count to have n-gons.

What's the problem with n-gons?

[Noobini]

think static models are fine but for animated characters, quads are best and n-gons not good (texture warping maybe?)

if you have an N-gon bending...the normals of the pseudo tri/quad in that N-gon might go screwy

[bobc4d]

nothing on flat geometry. but with curved surfaces it can show up with ugly ridges plus your UVs could look aweful

[Fenolis]

Simply put, n-gons and tris disrupt edge flow and can be a hassle to work with if you are applying subdivisions. Tris are somewhat forgiven because they resolve triangulation ambiguity (which sometimes causes normals-related issues with non-planar quads), but n-gons usually subdivide into a weird quad-pole due to the nature of the algorithm. There are methods to resolving such issues, such as adding supporting edge loops via insetting or bevels, but it's entirely within the realm of feasibility to not introduce problems in the first place.

[flcc]

Don't confuse primitives and polys. You can see n-gons as n-side polys with hidden edges. But in the end (GPU or renderer), the number of poly or tris will be the same.
 The real interest of n-gons is visual comfort.

[Fenolis]

Here is a description of how ngons can be used and why they usually aren't. 

 

[acey195]

Generally speaking completely flat N-gons are fine (as long as you keep them in houdini for logic manipulation :P)
if they get very concave they might get rendering issues though as it will do internal triangulation for the rendering, that in some rare cases will create self-intersecting geometry (only on the render side)

So for render performance keeping your geometry as n-gons does not really help..
HOwever, in terms of RAM in your Houdini session it can save a lot of data.