It has 5 water markers, which i remember is not good for performance. But that aside, looks really cool! =)
there was a guideline for watermarkers in one of the map contests, because basicly the mem-stats button was/is broken and it is hardly possible to measure the map performance.
If you know what you're doing, you can break those rules here and there, but need to be careful. The rules were just enforced on us to be 100% sure about map performance in this contest, leaving no room to fuck up for the contenders.
The problem with water markers is, each of them creates a water surface which is used for the calculation of reflections individually. So, if you have multiple of them on one screen, the performance will drop significantly, cause all of them have to be calculated at the same time. If you make sure that individual water surface are separated so you don't have more than 2 on a screen at a time, the influence on performance controlable. Just save some resources by keeping the render count in that area low, don't use more than 1-2 textures, don't pile splats and splines, and you are ok.