Add first performance measurements of dataflow API.

NOTES.md

@@ -4,6 +4,18 @@ A collection of stuff that we noticed during development.
 Useful later on two write a project report and to go back
 in time to find out why certain decisions where made.
 
+## 31.07.2019 - First benchmark of implementation
+
+We chose the implementation that allocates one invocation instance
+in one task when running. Our first benchmarks show that this
+is comparable to existing solutions, although we will investigate
+optimizations to the internals of the task scheduler to avoid
+unneeded copying and deeply nested tasks.
+
+Average case results of the image pipeline (executed on notebook):
+
+<img src="./media/7874c2a2_pipeline_speedup.png" width="400"/>
+
 ## 19.07.2019 - Colored tokens, recursion and where to put memory
 
 While implementing dataflow graphs we encountered some obstacles.