Fastest route JHB - Nairobi?
 

Having just dawdled my way down via Uganda, western Tanz and Malawi I must now, unexpectedly, return to Nairobi asap.

What is the fastest possible route from J'berg to Nairobi?

JHB - Lusaka - Tunduma crossing, then ...?? Or ...?

I'm in a Land Rover.

Thanks in advance for your assistance.
WR