Hi,

while I'm aware that numbers in
M0.123456,0.123456L1.123456,1.123456L1.123456,0.123456Z
are used internally by the browser to calculate shapes, it seems weird to me the we really need 1e-6 pixel precision. I'm wondering if reducing numbers precision in path strings can enhance DOM performances because of shorter d strings to be parsed.

This function:

(pathString, precision) => pathString.replace(/\d+\.\d+/g, s => parseFloat(s).toFixed(precision))

works well, but parsing the path string seems a waste of CPU cycles: maybe it'd be better passing a precision option to path.toString() and process all floats with f => f.toFixed(precision) before creating the output string.
In that case it would be nice to have d3.geoPath.precision([digits]) too.

What do you think about it?
Thanks!