Upgrading my HTPC - Best bang for my buck?

[gimme_vidyagames]

Hi guys,
I've got an existing HTPC which I built about a year ago, and it does a pretty great job at 720p, but my 1080p frame rate is hit or miss. Looking to upgrade (Metroid Prime deserves it), and I was wondering if I'd get more bang for my buck from upgrading my CPU or GPU. In other words, do you think Dolphin will benefit more from a CPU or GPU upgrade in my case? Is either upgrade option a futile waste of cash?
Current Specs:
Ubuntu x64, Dolphin 5.0
i5 6500 @3.2 Ghz
Zotac GTX 750 Ti Low Profile
8GB DDR3

Upgrade option 1: GTX 1050 Ti Low Profile
https://www.amazon.com/gp/aw/d/B01N2W8MJ9/ref=mp_s_a_1_fkmr1_1?ie=UTF8&qid=1487251273&sr=8-1-fkmr1&pi=AC_SX236_SY340_QL65&keywords=zotac+gtx+750+ti+low+profile

Upgrade option 2: i5 6600k @3.5 Ghz
https://www.amazon.com/gp/aw/d/B012M8M7TY/ref=mp_s_a_1_2?ie=UTF8&qid=1487251425&sr=8-2&pi=AC_SX236_SY340_QL65&keywords=lga+1151+i5&dpPl=1&dpID=41qV0dbcgOL&ref=plSrch