By @ellisjrosen

So, a typical snail moves at around 0.0048 km/h, and are around 1 cm tall. The snail in the image appears to be more than 3-4 stories tall, let's say 15 m. If the speed scales linearly with size, this snail could move at around 7.2 km/h.
So yeah, a very brisk walk for your life should just about keep you out of reach if you're in decent shape.
- r/theydidthemath
  
  They did the monster maths
  
  https://mander.xyz/c/theydidthemath
  https://mander.xyz/post/33834863
- So, sauntering is out?
  
  Saunter at your own peril.
- Your linked source doesn't appear to list that number (It lists 8 cm a minute).
  Perhaps you (or a large language model, if you're using one) has it mixed up with this:
  "Snails have been measured at speeds of 0.048 kilometres per hour."
  From this source.
  Also, 1 cm tall would be a very small snail... Approximately the size of your smallest fingernail.
  
  8 cm/min * 60 min/h * 1e-5 km/cm = 0.0048 km/h
  If I'm not completely mistaken.
  I'll admit that the "1 cm tall" is guesstimated based on my memory of the snails in my garden.
  The linked source also mentions that some snails can be up to ten times as fast as the typical 8 cm/min (0.0048 km/h), but those appear to be maritime snails, while the snail in the image seems to be terrestrial.
- I was hoping someone had calculated how quickly a snail that size would move, and you did not disappoint!
  
  the problem is snails harbor tons of parasites, the slime it leaves will just infect everyone in its wake.
- I was thinking this might be the case, but didn't want to do the math. Thank you.
- Unless it's a carnivorous snail

Spread salt on the road.
- Genius!

Glad to see medieval era humor still alive and well

A snail of that size would likely be much faster than the fastest human.
Source: my brain processing the thought in 3 seconds and spewing out this probability as "meh, speed scales with size in some ways"

People can survive a Snailpocalypse.
The Turtlegeddon, not so much, because turtles are actually surprisingly fast.

This reminds me of "day of the trifids" where the world is "invaded" by evil, aggressive,s walking plants. Not very frightening on its own, but at the same time a meteor flew over earth that blinded most of humanity leaving only a hand full sighted. That changes the premise quite a bit.