Some perf improvements when updating the layers list, also throttled color picker.

src/components/fields/ColorField.jsx

@@ -2,6 +2,7 @@ import React from 'react'
 import Color from 'color'
 import ChromePicker from 'react-color/lib/components/chrome/Chrome'
 import PropTypes from 'prop-types'
+import lodash from 'lodash';
 
 function formatColor(color) {
   const rgb = color.rgb
@@ -23,6 +24,15 @@ class ColorField extends React.Component {
     pickerOpened: false
   }
 
+  constructor () {
+    super();
+    this.onChangeNoCheck = lodash.throttle(this.onChangeNoCheck, 1000/30);
+  }
+
+  onChangeNoCheck (v) {
+    this.props.onChange(formatColor(v));
+  }
+
   //TODO: I much rather would do this with absolute positioning
   //but I am too stupid to get it to work together with fixed position
   //and scrollbars so I have to fallback to JavaScript
@@ -82,7 +92,7 @@ class ColorField extends React.Component {
       }}>
       <ChromePicker
         color={currentColor}
-        onChange={c => this.props.onChange(formatColor(c))}
+        onChange={c => this.onChangeNoCheck(formatColor(c))}
       />
       <div
         className="maputnik-color-picker-offset"

src/components/layers/LayerList.jsx

@@ -1,6 +1,7 @@
 import React from 'react'
 import PropTypes from 'prop-types'
 import classnames from 'classnames'
+import lodash from 'lodash';
 
 import LayerListGroup from './LayerListGroup'
 import LayerListItem from './LayerListItem'
@@ -116,6 +117,50 @@ class LayerListContainer extends React.Component {
     return collapsed === undefined ? true : collapsed
   }
 
+  shouldComponentUpdate (nextProps, nextState) {
+    // Always update on state change
+    if (this.state !== nextState) {
+      return true;
+    }
+
+    // This component tree only requires id and visibility from the layers
+    // objects
+    function getRequiredProps (layer) {
+      const out = {
+        id: layer.id,
+      };
+
+      if (layer.layout) {
+        out.layout = {
+          visibility: layer.layout.visibility
+        };
+      }
+      return out;
+    }
+    const layersEqual = lodash.isEqual(
+      nextProps.layers.map(getRequiredProps),
+      this.props.layers.map(getRequiredProps),
+    );
+
+    function withoutLayers (props) {
+      const out = {
+        ...props
+      };
+      delete out['layers'];
+      return out;
+    }
+
+    // Compare the props without layers because we've already compared them
+    // efficiently above.
+    const propsEqual = lodash.isEqual(
+      withoutLayers(this.props),
+      withoutLayers(nextProps)
+    );
+
+    const propsChanged = !(layersEqual && propsEqual);
+    return propsChanged;
+  }
+
   render() {
 
     const listItems = []