Lower FPS while in Arena vs Open world?

[Denexus]

My system isn't the best, but I get around 40-45FPS while in the open world fighting mobs (30-35FPS in cities) when all settings are set to 1 (Except texture & character view Distance). 

 

However when I enter 1v1 Arena, even before the fight starts my FPS is 15-16. This is before any effects or combat starts, and it just stays at 15-16fps the whole time.

 

Anyone have this same problem? Or have advice on how to resolve this FPS drop issue?

[maja]

Same problem here

[Denexus]

Any suggestions on how to fix this issue?