Well, I am already slowly starting to get back into coding me some Lisp games. There just isn't much else to do in my free time in this current global health crisis.
For the last week, I have been mostly scribbling notes on my reMarkable about ways to fix the engine troubles discussed in the last couple of articles. I have a few solutions that look really good on paper, so I'm just starting to explore them in code.
While it isn't that difficult of a problem to solve, the difficulty is in retrofitting the existing engine -- it'd be far too much work to solve that, both due to its size and complexity, as well as just the code quality in general with zero unit or integration tests.
For that reason, I am going to begin working on a new engine, that will share a lot of ideas with the previous, but will infact be rewritten from the ground up, with a better architecture and proper tests every step of the way. I'm not going to say much about the new design or what's different until I am confident enough in it, but what I worked out was a way to use structure-objects and arrays in the performance-sensitive areas that were previously using standard-objects and hash tables.
As the project progresses into more than just an idea, I will publish the code on my GitHub as usual. I just wanted to mention that I'm happy to be back, although I am taking precautions as to not get so burnt out again.