Let's see if Scratch 3.0 can lag! It can...
In case you didn't know, using the "If touching color" or "If color A is touching color B" then the game slows down more than a "If touching Sprite 1" is used. Then i create clones that use a color sensor forever, making the game lag. This lag device also worked in 2.0 and now, it seems, in 3.0 Now i still can't make those randomly generated worlds that use a million clones with color sensors. :(
