don't mention the number of allocations

this is primarily about unused capacity having its lifetime extended

library/alloc/src/vec/mod.rs

@@ -2811,11 +2811,11 @@ impl<T, I: SliceIndex<[T]>, A: Allocator> IndexMut<I> for Vec<T, A> {
 /// * perform the iteration in-place on the original allocation backing the iterator
 ///
 /// The last case warrants some attention. It is an optimization that in many cases reduces peak memory
-/// consumption and improves cache locality. But when a large number of big, short-lived
-/// allocations are created, only a small fraction of their items gets collected, no further use
-/// is made of the spare capacity and the resulting `Vec` is moved into a longer-lived structure
-/// this can lead to the large allocations having their lifetimes unnecessarily extended which
-/// can result in increased memory footprint.
+/// consumption and improves cache locality. But when big, short-lived allocations are created,
+/// only a small fraction of their items gets collected, no further use is made of the spare capacity
+/// and the resulting `Vec` is moved into a longer-lived structure this can lead to the large
+/// allocations having their lifetimes unnecessarily extended which can result in increased memory
+/// footprint.
 ///
 /// In cases where this is an issue, the excess capacity can be discarded with [`Vec::shrink_to()`],
 /// [`Vec::shrink_to_fit()`] or by collecting into [`Box<[T]>`][owned slice] instead, which additionally reduces
@@ -2827,8 +2827,7 @@ impl<T, I: SliceIndex<[T]>, A: Allocator> IndexMut<I> for Vec<T, A> {
 /// # use std::sync::Mutex;
 /// static LONG_LIVED: Mutex<Vec<Vec<u16>>> = Mutex::new(Vec::new());
 ///
-/// // many short-lived allocations
-/// for i in 0..100 {
+/// for i in 0..10 {
 ///     let big_temporary: Vec<u16> = (0..1024).collect();
 ///     // discard most items
 ///     let mut result: Vec<_> = big_temporary.into_iter().filter(|i| i % 100 == 0).collect();