Thanks a lot, David, for the feedback/files.
The first thing that stood out was the Anti Alias Still setting, instead of Animation. Still is typically sharper, but as long as no Motion Blur is calculated, a little bit softer helps.
If motion blur is widely given, the AA settings can go lower. If Geometry is sufficient, as mentioned in the Help Content, needs to be explored per scene, I would set it blindly.
Secondly, even you can render out mp4, or any kind of 8bit/compressed, just avoid it if you can. Of course, previews are always OK in that. I suggest to use OpenEXR for many reasons and go then to After Effects and render compressed versions from there. If that fails, based on to low or too high settings, it is a quick solve to try something else. In C4D you have to re-render, which is typically much more time investment.
I suggest as well to go 32bit/channel as it can hold more color details, in this case more gray values. With 8bit/channel you 256, and for some areas the differentiation among “tone values” might be not sufficient, and “banding” might hunt you down, i.e., ruins your efforts.
I have rendered frame 40 to 48 with – Sub Frame Motion Blur – I took the 49 “samples”, but one can certainly get away with much lower samples.
Motion Blur is as well available with other methods, but for texture based scenes, this might be a good idea. Texture animation will not work with some techniques, as in Vector Pass pipelines.
So, here is the file back, with a Ae file, where I have looped the few frames many times. Same outcome, but much faster, considering Motion Blur based rendering.
As a side note, if the texture animation and its direction is unchanged and the texture might flow in the image “kind of” evenly, the motion blur could be baked into the texture (Photoshop>Motion Blur, which is a directional blur and needs to be set into the movements directions). This is a hack and might not work always, but the rendering can be done without motion blur. Which might saves a lot of time. Once the motion blur is in the image, the speed of the image is relatively fixed as well. How much motion blur for the texture, render a test with a sharp texture (Checkerboard) and you have an idea about.