I get similar results with 2.10.1:

```scala
scala> th.pbench { appendWithVector(nums) }
Benchmark (60 calls in 740.1 ms)
  Time:    6.151 ms   95% CI 5.970 ms - 6.331 ms   (n=19)
  Garbage: 3.075 ms   (n=14 sweeps measured)
res0: Seq[Int] = Vector(0, 1, 2...
scala> th.pbench { appendWithListBuffer(nums) }
Benchmark (20 calls in 160.7 ms)
  Time:    1.888 ms   95% CI 1.802 ms - 1.974 ms   (n=16)
  Garbage: 3.050 ms   (n=2 sweeps measured)
res1: Seq[Int] = List(0, 1, 2...
```

```bash
➤ uname -a
Linux Turnbull 3.8.0-26-generic #38-Ubuntu SMP Mon Jun 17 21:43:33 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux
➤ java -version
java version "1.7.0_21"
Java(TM) SE Runtime Environment (build 1.7.0_21-b11)
Java HotSpot(TM) 64-Bit Server VM (build 23.21-b01, mixed mode)
```

Why do my Thyme-ings run so many fewer calls than yours?