Remove very old notes

Not up-to-date anymore and might be misleading.

docs/dev/todo/performance-ideas

@@ -1,6 +1,3 @@
-- Migrate scripts from bin/* to functions in bin/cdist-deploy-to
 - Use one pipe-shell for type execution
 - Parallelise gencode and code-run of all objects
 - Diff against local cache only instead of real target
-- Use only one ssh session?
-   - Can be indirectly improved via ssh config already!