Reduce startup jank, improve startup time (#568)

* Reduce jank on app startup

This feels a lot better on my 12" macbook (underpowered machine)

* Defer loading iso-639-1 and simple-concat

renderer/index.css

@@ -50,19 +50,22 @@ table {
 }
 
 @keyframes fadein {
-  from { opacity: 0; }
-  to   { opacity: 1; }
+  from {
+    opacity: 0;
+  }
+  to {
+    opacity: 1;
+  }
 }
 
-
 .app {
   -webkit-user-select: none;
   -webkit-app-region: drag;
   height: 100%;
   display: flex;
   flex-flow: column;
-  animation: fadein 0.3s;
   background: rgb(40, 40, 40);
+  animation: fadein 1s;
 }
 
 .app:not(.is-focused) {