Why is my video shaky after using Media Encoder?

I rendered a professionally digitized 8mm film today with Media Encoder CC after working on it in a Premiere Pro CC. In the editing process, I used the Neat Video plug-in to remove grain. In comparing the rendered video with the source, I noticed quite a bit of jerkiness in the rendered video. I have a late-2013 MacBook Pro with NVIDIA GeForce GT 250M 2048 MB. High Sierra is my OS. I discovered that I couldn't use the GPU to render the video because the Neat plug-in doesn't support it. Instead, I rendered the video with the CPU using 8 cores. My setting was H.264, Match Source--High bitrate. In comparing my unedited source video with the rendered edited version, I noticed differences. The FPS on the unedited video is 17 and the edited is 15. Also, the Mbit/s of the unedited video is 37.71, and the edited is 10.33. The format of the unedited video is JPEG. Do these differences explain the shakiness, or is there some other reason?