Imported video is extremely choppy in Premiere Pro CC 2019
Try setting the playback resolution to a lower setting. Depending on your periphery and the footage you're handling, it is quite normal for premiere to lag behind the realtime playback. Solutions for fluent playback might be:


Lowering the playback resolution (1/2, 1/4 or 1/16)
Using Proxies (smaller files, usually half the resolution. A quick google search tells you how to do that.)
Giving Premiere more RAM to play with and cleaning your cache.

-> You might need to go to edit -> purge and select purge all. Cached frames are frames that sit on a harddrive on your pc, so they don't have to be calculated every time they're played. Other then caching on the harddrive, premiere also caches into the RAM (random access memory) which acts like a very fast harddrive (although much smaller). Depending on how much RAM you can afford to assign to premiere (usually half as much as your total ram, preferably more than 8GB) you should up the amount dedicated to premiere. This setting sit in the memory section of the settings.