also the filter on OpenEmu Lite cranks up the fans quite a bit on my 2013 macbook pro wish there was a way to turn that off
There is, View → Select Filter.
also maximizing the game in full screen leads to it looking very blurry
I mean, that's why there are filters. You can either have the raw pixels or you can have (one of many different types of) blur, but there's no getting around the fact that this is a system that outputs at 240p.
I'm not sure what you mean by "upscale to my Retina resolution" in the context of the NES. Unless you're talking about things like xBR/Z, I could add one of those to the list of filters but it looks
so bad!
Edit: I'm pretty surprised GTU (the default filter) makes the fans on your MBP spin up though. I have a 2014 Macbook Air and OpenEmu takes up < 15% cpu running NES titles. I guess maybe because the resolution of your screen is so much higher?