Possible Clues:

• Sluggish one
• Won't go fast, even when driven at last
• ___ mail (e-mail alternative)
• Gastropod mollusc
• No fast food for the French?
• Householder making very slow progress
• Creature with one foot
• Crawler whose home has a helix pattern
• Slimy creature with a shell
• One's slow, normally, and inordinately long initially