So I'm just wondering what kind of measurements you did?

If I run those two things with a 1000 element Vector that I prepend to itself in the REPL with thyme, I get the opposite results.

```
scala> val v1 = (1 to 1000).toVector
scala> val w1 = th.Warm({ var res = v1; v1.reverseIterator.foreach(env => res = env +: res); res})
scala> val w2 = th.Warm(v1 ++: v1)
scala> th.pbenchOffWarm()(w1)(w2)
Benchmark comparison (in 34.48 s)
Significantly different (p ~= 0)
  Time ratio:    0.18835   95% CI 0.18569 - 0.19102   (n=20)
    First     291.4 us   95% CI 287.9 us - 294.8 us
    Second    54.88 us   95% CI 54.45 us - 55.31 us
```

First is the `reverse` code, and second is the `++:`