It's a little hidden, but this is out of MS research, and seems to be initially designed for ref-counted scripting languages. I'm not really sure how much they focused on multi-threaded stuff.
>We present mimalloc, a memory allocator
that effectively balances these demands, shows significant performance
advantages over existing allocators, and is tailored to support languages
that rely on the memory allocator as a backend for reference counting.
That's not what the quote means, really. They have best-in-class performance on both single- and multi-threaded workloads. It is just saying that the allocator supports a deferred_free callback, which is zero-overhead in the fast path and negligible overhead in the slow path.
>We present mimalloc, a memory allocator that effectively balances these demands, shows significant performance advantages over existing allocators, and is tailored to support languages that rely on the memory allocator as a backend for reference counting.
https://www.microsoft.com/en-us/research/publication/mimallo...