I understand you're trying to defend your choice, but even a GTX 760 can run modern games that look better than Golden Souls 3 at around the same or even higher framerates. And those games also use bloated engines, no less. It's just that GZDoom has gotten so poor, it slows things down to a crawl, and the visual fidelity does not justify the added performance burden. You should not look at this with pride, it actively harms the enjoyability of your game and it means less people can play it.
Just take a look at this benchmark video for the GTX 760 in 2020. Even years after it's sell-by date, it can still play a lot of the newer titles at around the same speed as Golden Souls 3. But look at the difference in visual quality.