diff --git a/docs/optimizing.md b/docs/optimizing.md
index 920c157..07f8e6f 100644
--- a/docs/optimizing.md
+++ b/docs/optimizing.md
@@ -33,7 +33,7 @@ Don't choose algorithm solely on the time complexity. GUI app needs smooth, not
 But it comes with cost. Modern browsers are already very smart on rendering. Using `contain`, you are trading onething off for another:
 
 - `layout` affects the reflow. This property usually won't make large change: mainline browsers already can incrementally reflow.
-- `style` affacts the style computation, is automatically enabled when using `container` property. Usually won't make large change too, unless you frequently change the styles (and/or your stylesheet is large and/or with complex selectors).
+- `style` affects the style computation, is automatically enabled when using `container` property. Usually won't make large change too, unless you frequently change the styles (and/or your stylesheet is large and/or with complex selectors), containing the computation may help performance.
 - `paint` affects the shading, the pixel-filling process. This is useful - the shading is resource-heavy - but the browser may need more buffers and more time to compose the final frame.
   - This containment may increase memory usage.
 - `size` says the size is not affected by outside elements and is defined. It hints the user agent can use the pre-defined size and/or cache the computed size (with `auto` keyword).