Ok, back again. Wanted to update my recent experience with updating my theme so others might get something out of it.
First, after updating to 1.3 I did not lose any of the styling I added in the custom styling panel. What I did have to add back to the header.php file was my Google and Adobe Typekit fonts. But everything else remained. I also created a new folder on my server named eunoia 2 and placed the latest eunoia version 1.3 file inside of it. This way I didn't have to delete my previously installed theme (just in case I needed to get any info from it). I DID use Backupbuddy to back everything up before I did ANYTHING. Also, when I uploaded the eunoia .zip to the new eunoia 2 folder, I created another folder and named it eunoia_1.3 and palced the .zip inside—then extracted the contents from the .zip. That's it. The new updated theme was now showing in my WP theme panel.
TOTALLY unconventional, but worked for me. I am still going to learn how to create child themes as Nick suggested. Just good practice. This was an easier option and a quick fix, but again, probably unconventional.
To conclude, updating the theme did not solve my portfolio image-loading issues. Still choppy, so I will optimize all my images as Nick suggested and see if this works. I will update shortly.