Function below 

pub fn below(codes: &[u32], len: usize) -> bool

Whether every one of codes is below len.

The obvious test is the largest code, and on the baseline x86-64 the release is built for that loop does not vectorize, because SSE2 has no unsigned 32 bit maximum. It was about half of Vector::gather on q01, where every filtered column asks it of the same positions. An or of every code is at least as large as each of them and does vectorize, so when it is below len every code is too. A filter’s positions over a full chunk of 8192 rows always pass that way, since len is then a power of two. Anything the or cannot settle takes the maximum.