The Anti-Theft Speed achievement is the second hardest achievement to earn in 12 Labours of Hercules III: Girl Power and can only be obtained on level 3-8.

First off, my advice is to leave this achievement (and Overlord) until you have completed the game, start up level 3-8, set the difficulty to casual, your only focus should be to prevent any resources being stolen from the two gold mines spawn points and the two berry bush spawn points.

As you are playing the level on casual difficulty, there is no timer or score to worry about and you can take as much time as you need, allowing you to prioritise collecting resource spawns and as long as you collect these within a second or two of appearing you can play the entire level without ever seeing a burglar let alone any resources actually being taken.