Do you have an estimate how complete your implementation is?
How does the performance compare with e.g. ECL or CLISP?
Did you run conformity tests, e.g. with https://gitlab.common-lisp.net/ansi-test/ansi-test?
Performance seems on par with clisp, but important optimizations are yet to be done, for example my program is still single-threaded
Can you please share more background information about the project, in particular why you wanted to take on this huge challenge, and why you didn't just start from an existing implementation, and why you chose C as the implementation language? Do you assume that you can still use the same GC with the addition of multi-threading?
About multi-threading: I still haven't thought about it much, but I'm optimistic; according to the paper, the algorithm is quite amenable to concurrency, since each object carries local information (the two refcounts), so some collection doesn't need global state. I agree, but we'll have to wait to see it in action