From my experience C# SOE are the fastest. It is also discussed here.

ArcGIS Server is developed in Java, how come .NET is the fastest?

closed as too broad by PolyGeo Feb 4 '16 at 23:25

Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. Avoid asking multiple distinct questions at once. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

  • Would you be able to quantify that experience in any way? If not, then I suspect that your question will be too broad and open to opinions because speed can be measured in many ways. By making your question about a specific test, which you describe, it will enable your question to qualify as focussed Q&A. – PolyGeo Feb 4 '16 at 23:25