I have been experiencing very big artefact problems and smudging when exporting a full quality Cinema4D animation render .mov from the premiere timeline as a streaming quality .mp4 with H264 (1500 kbps CBR). The workaround is to use the open source freeware Handbrake to encode from the .mov to .mp4. You can see the results in the picture. Apparently the problem is caused in PPro by the Main Concept codec, which can't handle camera pans and dollies or fast-moving content.
Handbrake uses the x264 encoder, which is arguably better than the MainConcept encoder.