Cinecom.net: Editing 4K on a Slow PC with Premiere Pro
In this video, Jordy Vandeput of Cinecom.net shows how to use the proxy workflows in the latest version of Premiere Pro CC to edit high resolution footage. This workflow is especially helpful for editing 4K on a slow computer or laptop. In fact, a proxy workflow might be the difference between being able to edit your video, and not being able to at all!
Slow computers and 4K video editing doesn't go together. But there's an option in Premiere Pro that creates low resolution proxies in a very fast workflow. —Jordy Vandeput, Cinecom.net
Source: https://www.cinecom.net/tutorials/editing-4k-slow-computer-premiere-pro