The main problem is that the 2 new buildd are Niagara machines which are not really stable. It left only 2 buildd which seems to be quit old and slow.
On my V240, the 3.13 kernel seems to be rock solid (I've been rebuilding the gcc package 3 times - 8hours build - without any issue).
Maybe what's missing is a couple of stable buildd to match the workload.