Weird presto sql things

MAX(x) is slower than

REDUCE(0.0, array_agg(x), (x,y) -> if(y > x, y, x), x ->x))

If is just a modified version of CASE WHEN, but with only one clause.

All subquery IN statements (Select *from table where column in (Select column from table)) are just inner joins.

Like I love presto, but wtf guys.