performance update

app/client/log.js

@@ -5,7 +5,8 @@ function sensor_data_collection() {
   }, {
     sort: {
       created_at: -1
-    }
+    },
+    limit: 100
   });
 }
 

app/client/state.js

@@ -20,7 +20,8 @@ function sensor_data_collection() {
   }, {
     sort: {
       created_at: -1
-    }
+    },
+    limit: 1
   });
 }