diff --git a/src/crew.gleam b/src/crew.gleam
index f7a42b2..45cfa10 100644
--- a/src/crew.gleam
+++ b/src/crew.gleam
@@ -319,6 +319,9 @@ pub fn parallel_map(
   timeout timeout: Int,
   with fun: fn(a) -> b,
 ) -> List(b) {
+  // we don't want to do the multiple subject trick here since that is
+  // potentially O(n^2)
+
   let unordered: List(#(Int, b)) =
     list
     |> list.index_map(fn(item, index) { fn() { #(index, fun(item)) } })
@@ -429,6 +432,9 @@ pub fn subscribe(pool: Name(PoolMsg)) -> Channel(a) {
 /// Work results arrive in completion order. It is your responsibility to handle
 /// the lifecycle and ordering.
 ///
+/// This adds a specific monitor to the selector to handle the case where the pool
+/// goes down, so it's better to prefer few channels over many.
+///
 /// ## Panics
 /// - If a worker or the pool crashes while executing work, the selector will
 /// panic with details about the crash.