I would like to extend a very grateful thank you to the EnergyPlus
development team for the improvements made to model run-time found in
EnergyPlus v.6

I have a very large project for which the energy model required just over 40
hours of run-time to complete a detailed model in version 5.

I added Output:Diagnostics,

CreateMinimalSurfaceVariables; and also changed any parameters that I could
to speed up the run-time, and it still took 13 hours in version 5 to
complete the run.

I simply transitioned this file into version 6 and the run completed in 2
hours!!!

If you are an energy modeler who has avoided adopting EnergyPlus due to
concerns about run-time, I would say that the developers have done a
wonderful job of addressing this issue. I have found that, with the most
recent version, models can be run in a reasonable amount of time regardless
of the complexity of the geometry and/or systems.

Many Thanks,

Jason Kirkpatrick, LEED AP