I did some experimenting and came up with [this rewrite](https://gist.github.com/akarnokd/9545150).
For a single producer, it runs, on average, the same ops/sec as your version. For the two producer case, mine runs about 10% more ops per second; which is not much considering the the perf test is only for overhead. However, the memory usage reduction for the single producer case might be worth it.