They'll all show some interrupt usage, that's part of how computers work. If your hardware's significantly oversized, especially CPU, relative to the amount of traffic you're pushing, it's probably a fraction of a percent. It's perfectly normal to have more interrupt load than that though, including well beyond what you're seeing if you start pushing a lot more traffic.
The interrupt load itself wasn't a problem with your Realtek NICs. Some of those NICs just fall apart under load, and the interrupt load increasing is just what happens when your NICs are under more load.