We had a similar problem with our network NT4 printer server. When we rebuilt the box, after a crash, large print jobs would pause in the middle for long periods of time. This is what we learned.
First check out KB article Q179156. You must have Service Pack 4 installed (or higher). This will give you the information to change ports used by the LPR printer. We learned that this is very important, particularly for large print jobs. When a job is sent to a dot-martix printer, it is sent line by line.
Second, this is a registry edit. Go to the following key.....
HKLM / System / CurrentControlSet / Control / Print / monitors / LPR Ports / Ports / / Timeouts
Here you will find two entries (CommandTimeout and DataTimeout). Change them both to 0 (zero). You will need to do this to any problem (or all) LPR ports.
After a reboot of your server, all should work correctly