My little server is capable of running smoothly with a half dozen players, half gooning around, and half spamming pulse, but only two players in the temple area on this map and it totally consumes processor resources.
The worst spots appear to be near those large trees either side of the open area. If one player is moving in those areas, and another player is watching the first player moving, the server becomes completely bogged down. Those trees and surrounds appear to be the problem. After reading the original mappers comments, it seems that many of the textures are converted photographs - possibly much higher quality than one wants in a map.
After looking inside the temple pk3 I discovered that there are 13 textures that are all over 700kB, all of which are used in that temple area, and many of which are transparent to some degree which means that the mossy mud areas on the ground are using two 1MB textures laid on top of one-another, as are the mossy pebbles on the bottom area.
Creating updated frames for one player watching another player moving in front of all these large textures seems to be the cause of the server drain.
I re-saved the textures by reducing many ofthem by 25% in dimension, then bringing them back to their original physical size, and wound up with a temple 0.5.5 which was only 17.7MB instead of 22MB. Running my reduced version of temple on my server seems to partly solve the problem, though I am no mapper and I may be imagining things.
Interestingly, if you look at the textures in the pk3 they are way more detailed that what you ever see in the game. The difference in image quality between the original and my reduced texture version when I dropped it by only about 25% can simply not be seen.
It would be nice if you could also lift the ceiling a bit in some future version - lisks, goons, maras and dretches need the height. Adding a few right-angled corners would also be helpful for gameplay, perhaps by extending this to an underground area? Extending those stairs that currently go from the cloisters to the tunnels could lead to an underground area very easily, and a second entry from the back of the second chasm would work nicely..