I think I know why, it's because you have grass sprites everywhere, but not visible. c_move detects the sprites and collides with them. Either turn of sprite collision in c_move/trace, or do as I told in my previous post.

if you only have 200 entities visible max, you really only need to make 200 grass sprites, not 1000. The level doesn't need to be filled if you dont see them anyway. If you create 200 grass sprites around the player at random locations, and you move the player forward, the grass sprites outside the visibility range should be relocated to some new location around the player that just appeared in visibility range.

That's the most effective way.