the digger is like psp in time (erase 3 lines it can be increased)
I was referring more to the relative speeds of things. For example, in DOS L1 / (Neo)Lemmix, if you were to make the first lemming in Fun 1 dig the instant that the second lemming touches the ground, by the time the second lemming reaches the digger, he will have dug 4 lines. On the other hand, in your game, he'll barely have dug two in the same time. On the other hand; a builder has a similar relative timing - if you were to use Tricky 1 and do the same setup with a builder, in both cases the lemming has more or less just placed his second brick - the
exact timing might not be the same, but the difference is negligable, unlike the very significant difference with the digger.
I do notice your game has a vertical playing area of about 290 pixels, or slightly less than double that of DOS / (Neo)Lemmix. If for simplicity's sake we just round that off to "double" exactly, then we account for that your digger removes 3 pixels (triple the height) instead of 2 (as would be expected for double resolution), then this means the digger has dug about 3 pixels (when adjusted for resolution). This does suggest that some of it is just a matter of perception, but overall the digger should be about 1/3rd faster than he currently is.