I'm not sure about that. You're right that there doesn't seem to have been much development going on in the last few years, but a quick Google Scholar search indicates that there are still papers being published with it.
I don't know if performance was ever much of a problem with AVIDA. It's a pretty light model, as far as I recall.
It is an intriguing system. I love the idea behind it and had good fun playing around with it back in secondary school. Also some interesting theoretical work that was done with it, biology-wise. Though of course, you always have to take model results with a big grain of salt (and have a careful think about what can and what can't be applied to Real Life).
I don't know if performance was ever much of a problem with AVIDA
What if interesting things only start happening when you run billions of organisms for billions of generations? Kinda like what's been happening in neural networks field since GPUs enabled training of huge models on huge datasets. Even small scale experiments, if you can run them 100 times faster, you can explore 100 times more configurations.
I also played with Avida a while back. It feels like the key people behind it just lost interest and moved on to other things, and there have been no others determined and talented enough to push it forward.
