Implemented dictionnary based file system to speed up the tests

docs/blog.rst

@@ -470,3 +470,27 @@ MUST be different ? How I handle when the explicitly have to be the same ?
 I seems that the purpose of the **ExactConceptParser** is to find exact match.
 I need another way to express that 'a' and 'b' can be the same.
 
+2019-11-21
+**********
+
+MemoryFS, is it a joke ?
+"""""""""""""""""""""""""""""
+
+I spent this day working on a improving the test performances. By default Sheerka
+persists its data on the file system (even if I said that where the data is saved)
+is not important for the sdp module.
+
+For each test, a folder in initialized to hold concepts information. And this folder
+is destroyed after usage. For almost every single test !
+
+So I decided to implement fs.MemoryFS. Information in memory is supposed to be
+faster than on the disk !
+
+I was very disappointed, after a afternoon of refactoring that it is actually slower
+than the native io implementation.
+
+Even now that I am writing it, I just can't believe it. I must I have implemented
+it wrong. But the profiling shows that the time is lost in the under layers of the
+FS library.
+
+It's a shame !