I'm sorry, but this is a very poorly reasoned article that does not engage with any of the serious work that's been underway to get reference counting competitive with tracing GC. This is evident from the very first point:

> 1. Updating reference counts is quite expensive.

> No, it isn't. It's an atomic increment, perhaps with overflow checks for small integer widths. This is about as minimal as you can get short of nothing at all. The comparison is the ongoing garbage collection routine, which is going to be more expensive and occur unpredictably.

First off, updating the reference count invalidates the entire cache line in which the reference count lives. For naive reference counting (which I'm assuming the author is talking about since they give no indication they're familiar with anything else), this generally means invalidating the object's cache line (and with an atomic RMW, to boot, meaning you need a bus lock or LL/SC on most systems). So right away, you have created a potentially significant cacheline contention problem between readers in multiple threads, even though you didn't intend to actually write anything. RC Immix, for example, tries to mitigate this in many creative ways, including deferring the actual reference count updates and falling back to tracing for reclamation when the count gets too high (to avoid using too many bits in the header or creating too many spurious updates).

Secondly, you know what's cheaper than an atomic increment or decrement? Not doing anything at all. The vast majority of garbage in most production tracing garbage collectors (which are, with the exception of Go's, almost exclusively generational) dies young, and never needs to be updated, copied, or deallocated (so no calling destructors and no walking a tree of children, which usually involves slow pointer chasing). Even where the object itself doesn't die young, any temporary references to the object between collections don't have to do any work at all compared to just copying a raw pointer, C style. This and bump allocation (which the author also does not engage with) are the two biggest performance wins that tracing garbage collectors typically have over reference counting ones, and solutions like RC Immix must implement similar mechanisms to even become competitive. You don't even need to go into stuff like the potential benefits of compaction, or a reduction in garbage managing code on the hot path (which are more dubious and harder to show) to understand why tracing has some formidable theoretical advantages over reference counting!

But what about in practice? Surely, the overhead of having to periodically run the tracing GC negates all these benefits?
Well, bluntly--no, not even close. At least, not unless you care only about GC latency to the exclusion of everything else, or are using something fancier (like deferred RC). You can't reason backwards from "Rust and C++ are generally faster than languages with tracing GCs on optimized workloads" to conclude that reference counting is better than tracing GC--Rust and C++ both go out of their way to avoid using reference counting at all wherever possible.

None of this is secret information, incidentally. It is very easy to find. The fact that the author is apparently so incurious that they never once bothered to find out why academics talk about tracing GC's performance being superior--and the fact that it was so dismissive about it!--makes me pretty doubtful that people are going to find useful insights in the rest of the article, either.