When you do: RUN test.r OpenEdge will do the following steps per directory in the Propath:
1) Search for test.r
2) If test.r is not found then replace .r with .r and search again, so it will search again for test.r
This second search is not necessary, because this filename is already not found in the first search.
This behavior is noticed in Windows environment with OE 10.2B and 11.3 by using Process Monitor (Sysinternals).
This will give disk latency with a large propath and with a lot of files that can't be found.
Step 2; test.r does not replace .r with .r, but it is running what you have typed behind the run.