It defilitely lags a bit on desktop (as said before) and it seems confused about whether it should scroll or zoom when I tried swiping on the touchscreen of my laptop, eventually becoming completely unresponsive until a refresh of the page.

Also, maybe leave scrolling for scrolling and have click+drag as the zoom function (on desktop I mean)? It feels natural on maps to zoom with the wheel, but this looks tempting to scroll and then when you try, it goes all zoomy.

When clicking on the "+" I very stupidly tried to hunt down the escaping dot daring me to "drag it". This might be a problem on my part.