Oh yeah - The latest Gen I7 CPU
Uninstalled and reinstalled (with no updates) - Issue fixed. Guess I wont do updates when they first come out.
Updates should have nothing to do with your render quality. And, even with updates, there's no read 1920x1080 video should ever look horrible when rendered.
Are you rendering as in using Export & Share to output a finished video or are you rendering as in doing a hard render of the timeline?
There are a number of factors that could play into your situation including the model of camcorder your video is coming from, your project settings, the quality level you have your Monitor panel set to and your Export & Share settings.
So, in the name of troubleshooting, I thought of something else this morning that I forgot I did. I did a video card update just the other day, also.
I use two camera's a Samsung Tough recording at 1080 30FPS for my main shooter. Then a GoPro 4 Silver recording at 1080 60FPS, which I use for PIP. I recording un-boxing videos about once a month for my YouTube channel.
Now please don't forget I have been recording like this for awhile now and never experienced these problems. The huge issue I had (until I uninstalled and re-installed) was that every time the timeline would hit the GoPro *.MP4 video the play back would be completely unusable to work in. Once it went back to the Samsung *.MOV the playback would resume back to normal. so, then I would try and "hard" render the timeline, but, it would take an hour (give or take) to render. I honestly have never hard to render a timeline EVER to work in it with this same setup that I always use.
So, what I will do in a few is try and figure out how to uninstall my video card update. Its defiantly a update, either the video of Adobe. To, add though, when i uninstalled Premier it did help tremendously, but, it wasn't back to normal.
Side note - the only two different things I did in this video was, I adjusted the distortion / contour to -29 on the GoPro timeline to get rid of the "fisheye" effect. Then I did actually use the PIP effect, I just resize by dragging the window smaller and shoving it in the up right of the work space.
Okay, so, I think I figured it out. I think its the lens distortion / curvature and the PIP together. I first removed the curvature from the original video and it helped but not enough. I then completely deleted the PIP track and re-added then applied the PIP effect (remember before I just used the drag and resize method) and this helped a ton (back to normal). But, even after using the true PIP feature and then re-applying the curvature the playback went back to being choppy.
That's interesting! Great troubleshooting, Peter!