As soon as E1000PKT.COM gets loaded on my system, a red "E" gets displayed the upper right corner of the screen.
Don't know what that means, it works just fine.

Figured out E1000PKT.COM v0.5 that is found everywhere was compiled with debug output enabled.
As the source is available, I recompiled it with disabled debug output: Success! The red "E" is gone, and it is a little bit smaller.
Did not check if throughput changed.