We have recently launched a new core type for bigadv work units. We're forking A5 off from our A3 core to make a core that specializes in bigadv workunits. In particular, new A3 and A4 cores use more RAM per thread which makes large-memory calculations very memory inefficient in those cores. A5 does not have this issue and looks to be a good general fix for big RAM (eg bigadv) calculations.
However, to be able to use the new A5 core, one needs to use an updated client: 6.34 or later.
We are shutting down A3 bigadv in the next day, so please update your clients if you wish to continue running bigadv work units (to be clear, all issued A3 bigadv work units will be accepted until their deadlines. We are terminating new bigadv work unit assigns). Older clients will be redirected to standard A3 SMP work units; the switchover will allow us to push an update to the standard A3 core and release a large number of new A3 work units that have been in early testing.