SF story about a planet inhabited by *extremely slow* humanoids...?

Question

This must be quite an oldish story because I read it as a kid in the 70s. Now I need it badly and can't find it. I read a translation, and translation was named Invincibles or Invincible, but that may possibly not be original title (and it's not S. Lem's Invincible novel)

Gist:

Earth people are conquering the universe, planet by planet, and from one planet the vanguard sends only a short message, before proceeding to another planet: "Invincible" (as in "these guys are invincible")

Now, the earthlings were very curious about this because they haven't yet met a civilization they couldn't conquer. When they arrived, they found a relatively advanced civilization of smallish humanoids (they had technology, cities, trains were mentioned, etc.). But the inhabitants were so slow that they (and their trains, etc.) looked almost frozen in time. They wouldn't even notice earthlings when they arrived and moved around. You'd have to stand still for like 15-20 minutes for the native to slowly move their eyes in your direction.

I don't remember the plot from that point onward, I only remember that eventually the earthlings gave up the idea of conquering/occupying these guys and left, concluding that they are indeed "invincible", in a sense. Although they could easily wipe out the native civilization (natives would not stand a chance at their speed), apart from that unnecessary destruction, there was nothing else the earthlings could do with these people. They were simply unusable for any kind of exploitation.

Answer 1

The story is "The Waitabits", a novelette by Eric Frank Russell. It was first published in Astounding Science Fiction, July 1955, which is available at the Internet Archive.

Earth people are conquering universe, planet by planet, and from one planet the vanguard sends only a short message, before proceeding to another planet: "Invincible" (as in "these guys are invincible")

'Planet fourteen on Boydell's list. He has given it the name of Eterna and don't ask me why. The code formula he's registered against it reads 0/1.1/D.7. That means we can live on it without special equipment, it's an Earth-type planet of one-tenth greater mass and is inhabited by an intelligent lifeform of different but theoretically equal mental power. He calls this lifeform the Waitabits. Apparently he tags everything and everybody with the first name that pops into his mind.'

'What information does he offer concerning them?'

'Hah!' said Markham, pulling a face. 'One word. Just one word.' He paused, then voiced it. 'Unconquerable.'

'Eh?'

'Unconquerable,' repeated Markham. 'A word that should not exist in scout-language.' At that point he became riled, jerked open a drawer, extracted a notebook and consulted it. 'Up to last survey, four hundred twenty one planets had been discovered, charted, recorded. One hundred thirty seven found suitable for human life and large or small groups of settlers placed thereon. Sixty-two alien lifeforms mastered during the process.' He shoved the book back. 'And out there in the dark a wandering tramp picks a word like unconquerable.'

When they arrived, they found a relatively advanced civilization of smallish humanoids (they had technology, cities, trains were mentioned, etc.) But the inhabitants were so slow that they (and their trains etc) looked almost frozen in time...

A couple of miles away the streamlined express came tearing around the base of a hill at nothing less than one and a half miles per hour. The men remained staring incredulously for ten minutes during which time the phenomenon covered a full quarter mile.
<br.[. . . .]

The train consisted of four linked metal coaches and no locomotive, the source of power not being evident. The tiny cars, less than the height of a man, rolled by holding a score of crimson-faced, owl-eyed creatures some of whom were looking absently at the floor, some at each other, out the sides, anywhere but directly at the great invader atop the bluff.

...there was nothing else Earthlings could do with these people... they were simply unusable for any kind of exploitation...

'Suppose Walterson and the others find this lousy world rich in the things we need,' he persisted. 'How are we going to get at the stuff short of excavating it ourselves? The Waitabits form a big and probably willing labour force but what's the use of them if the most rudimentary job gets completed ten, twenty or fifty years hence? Who's going to settle here and become a beast of burden as the only way of getting things done in jig time?'