I work with in Lawrence Technological University and I had a student come up to me today explaining a problem he was having with in Flash CC. The problem was when he was drawing a circle real fast with the brush tool it would render in a square formation. But, when drawing the circle slow it would render perfect as how he drew it. Also, on the mac version of Adobe it is running fine but on pc it creates this problem. Last thing is that Adobe CC is running with in a Lenovo W510 with upgraded ram so it is probably not the computer.
Moving discussion to Flash forum.
This is fixed in the Flash Pro CC update - 13.0.1 that is availble for download.
Please navigate to Help->Updates menu to install the updates.
Hope this helps.