I think part of the issue was walking with little children. Walking half the distance takes 15 minutes. Then half the remaining distance takes 15 minutes. Then half the ...
One thought would be to head to the Four Seasons and walk in aircon comfort through the Four Seasons and on to the connected Hilton before popping out again on Orchard by the far exit (assuming this is still possible). There's a certain amount of elevation change with escalators, as I recall.