most compact folders are slow. they can be made much quicker with areo bars or bull bar mods. drop tend to interfer with fold.
a brompton withbull bars about44cm or wider fold just as flat as a standard bike as the bars fit either side of the front folded wheel.
i have put bullbars or silumar on mezzos,broptoms,downtube, and mission space genie with good results. add jokacks and your well away