Comment 8 for bug 1401707

So I have done some debugging to come up with the following.

1. the fix for bug 1401983 is needed, this helps a lot with the pxeconfig
2. removal of WindowsPXEBootMethod also helps a lot

Still twistd CPU% is very high, even without nodes booting. This is because of all of the RPC calls that are made from the region to the cluster anytime a web request comes it.

1. DescribePowerTypes is called 4 times per request. I implemented a quick caching of this method and it help lower the CPU usage of twisted.

2. ListBootImages which is a very heavy process on the cluster is called very often. This method needs to be cached as well. I think this should be cached on the region and the cluster. The cluster knows the last time it updated the boot images, so it only needs to update its cache on start and after each sync of boot images. The region can also cache this RPC call for a minute so not to hit the cluster every so often, but when the region does ask it will already be cached on the cluster.