GPU Memory Read Rate (Bytes per Second)

This counter shows the rate within the current period that the GPU is reading data from the system memory bus in bytes/sec.

A constantly high value means the GPU may be accessing memory too often. On shared memory systems it is possible that this value may be low, but the whole system might be still memory bandwidth limited.

If this value is high, then you should reduce number of memory reads. This can be achieved by removing texture fetches from the shaders or making textures more cache efficient using texture compression. There can be a small overhead reading vertex data from the Parameter Buffer. In these cases try to reduce the number of polygons or the number of varyings used in the shaders.