I'm with Princess on this one. I have a i7-6700k and it handles Premiere just fine. If you're having issues with playing footage in the timeline it's usually b/c of the codec your footage is in. You want a high bit rate codec, Prores, DNxHR, and GoPro Cineform are good codecs and industry standards for editing. If your footage isn't in this codec natively, you can use Premiere's Proxy settings to transcode it automatically. If you really want to upgrade, I'd wait for Zen 2 or Intel to release a new architecture.