10 times

### next sibling = 0

-- 10times --
real    0m7.489s
user    0m0.050s
sys     0m0.010s

-- 100times --
real    1m4.832s

### 5

-- 10times --
real    0m9.354s
user    0m0.020s
sys     0m0.030s

-- 100times --
real    2m10.516s

### 15

-- 10times --
real    0m9.500s
user    0m0.040s
sys     0m0.020s

-- 100times --
real    3m51.117s

### 50

-- 10times --
real    0m10.757s
user    0m0.030s
sys     0m0.010s

-- 100times --
real    9m58.381s

### 75

-- 100times --
real    17m42.983s

### 100

-- 100times --
real    33m14.243s
