People often ask why deleting files is faster than creating files. The answer is because the bulk of the file's data is NOT erased, because that's considered wasted effort. When the new file comes along it will write over the data, completely unaware of what was once there. So actually blanking out the old data doesn't really accomplish anything and the "delete" is really fast by just dealing with the file listing paperwork.

...unless there's privacy concerns that warrant actually clearing the data, specifically because preventing undelete from being possible is the goal. This is sometimes called "secure delete". But if you're uninstalling a video game, who cares?