Rendering in Premiere Pro using 500%+ of CPU

In the past few days Premiere started running a lot slower than normal, with especially slow render times. I was using an older version of Premiere Pro CC so I updated to the new 2017 version. I am still running into the same problems. Editing seems to be better in general, although I still get some intermittent lag while working on the timeline. When I start any render process the CPU usage immediately jumps to over 500%. I am using an older Macbook pro, specs below.

MacBook Pro (Retina, 15-inch, Late 2013)

Processor - 2.3 GHz Intel Core i7

Memory - 16 GB 1600 MHz DDR3

Graphics - NVIDIA GeForce GT 750M 2048 MB

Any help or ideas on a solution would be great. Thanks.