Guild Wars 2

From: http://wiki.guildwars2.com/wiki/Command_line_arguments

-umbra gpu
Forces the use of umbra’s GPU accelerated culling.
In most cases, using this results in higher cpu usage and lower gpu usage decreasing the frame-rate.

“In most cases”. I’m confused though as to why it would have the effect of increasing CPU usage and decreasing GPU usage.

My expectations if it worked properly would be to see less CPU usage, more GPU usage, and that if it didn’t work, it would simply give similar performance as without the argument.

Is there any information as to how to see if this even works properly? Any requirements to make it work properly if it doesn’t? Any cases where it actually “has” worked? I’m guessing it has to have some kind of reason to still be implemented.

During the beta the setting was added I believe, and some developers wanted those of us with performance issues to experiment using that argument by testing locations of bad FPS with it on and off.

The command is meant to turn on or off Umbra 3, a bit of software written by a different company that was included in GW2, the reason why it says it will result in higher CPU usage is because Umbra 3 does not use the GPU at all, it runs entirely on the CPU. In any MMO, the CPU is often already working too hard as it is, due to lots of players on the screen. So if your CPU is already overloaded as it is, putting more onto your CPU will slow the game down even further, probably not much on a high end system, but on a low end or old processor it might be very noticeable.

I don’t know if the setting still does anything post-beta, though.

Hmm, so this means the current culling method isn’t Umbra, but something else?

The note says “In most cases” though; I’m mainly curious as to what cases it didn’t have increased CPU usage, if any.

The setting does manage to do something though (FPS drops a bit with it).