Hard to answer considering the number of variables impacting. pg_bulkload quotes 18MB/s for parallel loading on DBT-2 (221s to load 4GB), and 12MB/s for the built-in COPY (with post-indexing, that is first import all the data then enable and build the indexes)
> Is it possible to import data directly from CSV files?
Yes, the COPY command can probably be configured to support whatever your *SV format is. There's also pg_bulkload (which should be faster but works offline).