I can't put my finger on it but something in the monospaced font used for numbers is making it slower to read. In particular the bolded slashed 0 hurts readability as it basically looks like a big blob with tiny spaces in it. I attached a comparison (fake numbers), lunch money is on the left. The background/text color combo is also lower contrast which may contribute to this effect.
New user but extremely impressed so far at what one person was able to do. Will probably subscribe after trial ends :)