What's the reason for Q*Bert's playfield being asymmetrical?

[azure]

The gap down the playfield is wider between some cubes. I'm wondering why couldn't it have been perfectly symmetrical?

 

The gap is marked in the screenshot:

[Thomas Jentzsch]

You cannot create a single PF pixel gap in the middle without making the playfield asymmetrical. So technically the playfield is completely symmetric. And that saves a lot of valuable CPU time.