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.