In 3.2,

• for journaling:
  • all log records up to 128KB are buffered / consolidated (i.e. no need to first hit contention ...)
  • log records remain buffered until a checkpoint, a j:true update or 100ms, whichever comes first.
• WT cache
  • default configuration will change to (60% of RAM minus 1GB) or 1GB, whichever is larger. This is less than or equal to the 3.0 setting for systems with up to 10GB of RAM, and more otherwise.