Optimize append and remove options

src/components/select/utils.js

@@ -0,0 +1,14 @@
+export function debounce(fn) {
+    let waiting;
+    return function() {
+        if (waiting) return;
+        waiting = true;
+        const context = this,
+            args = arguments;
+        const later = function() {
+            waiting = false;
+            fn.apply(context, args);
+        };
+        this.$nextTick(later);
+    };
+}