docs: explain why tooltips, popovers, toasts, and carousels are opt-in

site/src/content/docs/components/carousel.mdx

@@ -8,7 +8,7 @@ toc: true
 
 - The carousel is a slideshow for cycling through a series of content, built with CSS 3D transforms and a bit of JavaScript. It works with a series of images, text, or custom markup. It also includes support for previous/next controls and indicators.
 
-- For performance reasons, **carousels must be manually initialized** using the [carousel constructor method](#methods). Without initialization, some of the event listeners (specifically, the events needed touch/swipe support) will not be registered until a user has explicitly activated a control or indicator.
+- For performance reasons, **carousels must be manually initialized** using the [carousel constructor method](#methods). Auto-initializing every carousel on page load would register touch, swipe, scroll, and resize event listeners even for carousels that may not be visible or interactive yet. Without explicit initialization, some of these event listeners (specifically, the events needed for touch/swipe support) will not be registered until a user has explicitly activated a control or indicator.
 
   The only exception are [autoplaying carousels](#autoplaying-carousels) with the `data-bs-ride="carousel"` attribute as these are initialized automatically on page load. If you’re using autoplaying carousels with the data attribute, **don’t explicitly initialize the same carousels with the constructor method.**
 

site/src/content/docs/components/popovers.mdx

@@ -10,7 +10,7 @@ Things to know when using the popover plugin:
 
 - Popovers rely on the third party library [Popper](https://popper.js.org/docs/v2/) for positioning. You must include [popper.min.js]([[config:cdn.popper]]) before `bootstrap.js`, or use one `bootstrap.bundle.min.js` which contains Popper.
 - Popovers require the [popover plugin]([[docsref:/components/popovers]]) as a dependency.
-- Popovers are opt-in for performance reasons, so **you must initialize them yourself**.
+- Popovers are opt-in for performance reasons, so **you must initialize them yourself**. Like tooltips, each popover creates a [Popper](https://popper.js.org/docs/v2/) instance that tracks scroll and resize events. Auto-initializing every popover on page load would add unnecessary overhead on pages where popovers are not used or where only a few elements need them.
 - Zero-length `title` and `content` values will never show a popover.
 - Specify `container: 'body'` to avoid rendering problems in more complex components (like our input groups, button groups, etc).
 - Triggering popovers on hidden elements will not work.

site/src/content/docs/components/toasts.mdx

@@ -10,7 +10,7 @@ Toasts are lightweight notifications designed to mimic the push notifications th
 
 Things to know when using the toast plugin:
 
-- Toasts are opt-in for performance reasons, so **you must initialize them yourself**.
+- Toasts are opt-in for performance reasons, so **you must initialize them yourself**. Auto-initializing every toast on page load would register timers and event listeners even when no toasts are visible, adding unnecessary overhead on pages that create toasts dynamically or only in response to user actions.
 - Toasts will automatically hide if you do not specify `autohide: false`.
 
 <Callout name="info-prefersreducedmotion" />

site/src/content/docs/components/tooltips.mdx

@@ -9,7 +9,7 @@ toc: true
 Things to know when using the tooltip plugin:
 
 - Tooltips rely on the third party library [Popper](https://popper.js.org/docs/v2/) for positioning. You must include [popper.min.js]([[config:cdn.popper]]) before `bootstrap.js`, or use one `bootstrap.bundle.min.js` which contains Popper.
-- Tooltips are opt-in for performance reasons, so **you must initialize them yourself**.
+- Tooltips are opt-in for performance reasons, so **you must initialize them yourself**. Unlike most other Bootstrap components, tooltips and popovers are not automatically initialized because each one creates a [Popper](https://popper.js.org/docs/v2/) instance that tracks scroll and resize events. Auto-initializing every tooltip on page load would add unnecessary overhead on pages where tooltips are not used or where only a few elements need them.
 - Tooltips with zero-length titles are never displayed.
 - Specify `container: 'body'` to avoid rendering problems in more complex components (like our input groups, button groups, etc).
 - Triggering tooltips on hidden elements will not work.