Where are you getting either of these figures?

The up to 18km/s is from the linked shield.

Up to 0.1c is from the interstellar spaceship competition "cruise" speeds (also used 0.01c) as presented in their deck.

They're a few orders of magnitude difference.

Also, there's plenty of resources around on interstellar travel that shows interstellar dust/debris is going to be a huge problem.

For example Atomic Rockets, which has a bunch of good reference materials (albeit poorly organized), or the Astronomy Cafe

https://sten.astronomycafe.net/at-what-speed-does-the-inters...