GS Is Bottleneck
GS Is Bottleneck metric represents the percentage of time that the geometry shader (GS) stage is a bottleneck. This is the percent of time the GS unit is stalling the Vertex Shader/Domain Shader (VS/DS; upstream unit) and starving the Stream Output Logic (SOL; downstream unit).
If GS Is Bottleneck is 90, then the geometry shader stage is a bottleneck (stalling both the upstream and downstream units) 90% of the time.
A geometry shader can output new primitives from its input primitives. New vertices can be generated from a set of input vertices. However, generating too many new primitives can result in a bottleneck in the GS stage. In the Intel® GPA Frame Analyzer, try editing the geometry shader in the Shaders tab. For example, try reducing the number of primitives that the geometry shader generates.
VS Is Bottleneck
Sampler Is Bottleneck