fix(volumeLoad): should not have missing slices when loading (#3287)

* fix(volumeLoad): should not have missing slices when loading

* add review comments

platform/viewer/public/config/default.js

@@ -18,7 +18,9 @@ window.config = {
   maxNumRequests: {
     interaction: 100,
     thumbnail: 75,
-    prefetch: 10,
+    // Prefetch number is dependent on the http protocol. For http 2 or
+    // above, the number of requests can be go a lot higher.
+    prefetch: 25,
   },
   // filterQueryParam: false,
   dataSources: [