diff --git a/CHANGELOG.md b/CHANGELOG.md
index b8807ec..47ab287 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,8 +1,18 @@
+# v0.16 2018-04-04
+
+* Change back to use MongoDB 3.2.19.
+* Add info about MongoDB oplog for large scale usage.
+* Reorder docs to be above settings.
+
+Thanks to GitHub user xet7 for contributions.
+
 # v0.15 2018-03-15
 
 Change snap to previous MongoDB version 3.2.18 because of data loss:
 https://github.com/wekan/wekan-mongodb/issues/9
 
+Thanks to GitHub user xet7 for contributions.
+
 # v0.14 2018-03-06
 
 * Use MongoDB 3.2.19
diff --git a/docker-compose.yml b/docker-compose.yml
index afc2e24..61dcdc2 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -38,7 +38,7 @@ services:
   wekandb:
     # All Wekan data is stored in MongoDB. For backup and restore, see:
     #   https://github.com/wekan/wekan/wiki/Export-Docker-Mongo-Data
-    image: mongo:3.2.18
+    image: mongo:3.2.19
     container_name: wekan-db
     restart: always
     command: mongod --smallfiles --oplogSize 128
@@ -67,23 +67,51 @@ services:
     # For running Wekan in different port like 3000, use: 3000:80
     ports:
       - 80:80
-    #---------------------------------------------------------------
-    # Change ROOT_URL to your real Wekan URL, for example:
-    #   http://example.com
-    #   http://example.com/wekan
-    #   http://192.168.1.100
-    #---------------------------------------------------------------
-    # Email settings are required in both MAIL_URL and Admin Panel,
-    #   see https://github.com/wekan/wekan/wiki/Troubleshooting-Mail
-    #   For SSL in email, change smtp:// to smtps://
-    #---------------------------------------------------------------
-    # Not needed on Docker, but if you had installed from source,
-    #   you could also have setup Wekan Node.js port at localhost
-    #   with setting: PORT=3000
-    #   and have Nginx proxy to port 3000, see Wekan wiki.
     environment:
-      - MONGO_URL=mongodb://wekandb:27017/wekan
+      #---------------------------------------------------------------
+      # == ROOT_URL SETTING ==
+      # Change ROOT_URL to your real Wekan URL, for example:
+      #   http://example.com
+      #   http://example.com/wekan
+      #   http://192.168.1.100
+      #---------------------------------------------------------------
       - ROOT_URL=http://example.com
+      #---------------------------------------------------------------
+      # == PORT SETTING ==
+      # Not needed on Docker, but if you had installed from source,
+      #   you could also have setup Wekan Node.js port at localhost
+      #   with setting: PORT=3001
+      #   and have Nginx proxy to port 3001, see Wekan wiki.
+      #---------------------------------------------------------------
+      # - PORT=3001
+      #---------------------------------------------------------------
+      # == MONGO URL AND OPLOG SETTINGS ==
+      # https://github.com/wekan/wekan-mongodb/issues/2#issuecomment-378343587
+      # We've fixed our CPU usage problem today with an environment
+      # change around Wekan. I wasn't aware during implementation
+      # that if you're using more than 1 instance of Wekan
+      # (or any MeteorJS based tool) you're supposed to set
+      # MONGO_OPLOG_URL as an environment variable.
+      # Without setting it, Meteor will perform a pull-and-diff
+      # update of it's dataset. With it, Meteor will update from
+      # the OPLOG. See here
+      #   https://blog.meteor.com/tuning-meteor-mongo-livedata-for-scalability-13fe9deb8908
+      # After setting
+      # MONGO_OPLOG_URL=mongodb://<username>:<password>@<mongoDbURL>/local?authSource=admin&replicaSet=rsWekan
+      # the CPU usage for all Wekan instances dropped to an average
+      # of less than 10% with only occasional spikes to high usage
+      # (I guess when someone is doing a lot of work)
+      #---------------------------------------------------------------
+      - MONGO_URL=mongodb://wekandb:27017/wekan
+      #---------------------------------------------------------------
+      # - MONGO_OPLOG_URL=mongodb://<username>:<password>@<mongoDbURL>/local?authSource=admin&replicaSet=rsWekan
+      #---------------------------------------------------------------
+      # == EMAIL SETTINGS ==
+      # Email settings are required in both MAIL_URL and Admin Panel,
+      #   see https://github.com/wekan/wekan/wiki/Troubleshooting-Mail
+      #   For SSL in email, change smtp:// to smtps://
+      # NOTE: Special characters need to be url-encoded in MAIL_URL.
+      #---------------------------------------------------------------
       - MAIL_URL=smtp://user:pass@mailserver.example.com:25/
       - MAIL_FROM='Example Wekan Support <support@example.com>'
     depends_on: