Well, all I can offer here is my experience. As a matter of fact I am currently working on something similar (i.e an ETL with text files). We're essentially taking a lot of text files and loading their lines up into a PostgreSQL database. This is our setup :
- Intel Xeon 8 cores + SSD
- Files and app on the same machine
- Remote database
We're able to fetch, parse and load 26 millions file lines and creating specific database indices in about 12 minutes, which is about 1.3GB worth of files and 3GB in database. On a much crappier mono-core and HDD setup we can do it in about 40 minutes.
The good thing about Akka is that it will allow you to save up resources and scale more since several actors can share one thread.