If there are no optimistic updates to apply, return immediately.

CHANGELOG.md

@@ -4,6 +4,7 @@ Expect active development and potentially significant breaking changes in the `0
 
 ### vNEXT
 
+- Avoid extra `assign` when there are no optimistic updates present. [PR #597]((https://github.com/apollostack/apollo-client/pull/597)
 - ...
 
 ### v0.4.13

src/store.ts

@@ -134,6 +134,9 @@ export interface ApolloReducerConfig {
 }
 
 export function getDataWithOptimisticResults(store: Store): NormalizedCache {
+  if (store.optimistic.length === 0) {
+    return store.data;
+  }
   const patches = store.optimistic.map(opt => opt.data);
   return assign({}, store.data, ...patches) as NormalizedCache;
 }