What do you mean by "as soon as possible" ?
How critical is time? half a second? a second?
If time is really critical, then you'll have to delve in the arcane techniques used in motion detect.
why do you need metering/focusing every 5 seconds?
is this to be ready to shoot when requested by the USB?
I don't know if you want tu use uBasic or LUA, but in pseudo-code I wouldo something like:
count=0
loop
loop
wait 0.1 seconds
count=count+1
if count=50 then
meter & focus
count=0
endif
until the usb says to shoot
take the shot
until 1=2