Avoid subscribing static components

CHANGELOG.md

@@ -6,6 +6,8 @@ _The format is based on [Keep a Changelog](http://keepachangelog.com/) and this
 
 ## Unreleased
 
+- Performance optimization for fully static (no function interpolation) styled-components by avoiding using `ThemeConsumer` since it isn't necessary, by [@mxstbr](https://github.com/mxstbr) (see [#2166](https://github.com/styled-components/styled-components/pull/2166))
+
 ## [v4.0.3] - 2018-10-30
 
 - Interpolating a styled component into a string now returns the static component selector (emotion cross-compat)

src/models/StyledComponent.js

@@ -74,6 +74,10 @@ class StyledComponent extends Component<*> {
 
   renderOuter(styleSheet?: StyleSheet) {
     this.styleSheet = styleSheet;
+    const { componentStyle } = this.props.forwardedClass;
+
+    // No need to subscribe a static component to theme changes, it won't change anything
+    if (componentStyle.isStatic) return this.renderInner();
 
     return <ThemeConsumer>{this.renderInner}</ThemeConsumer>;
   }