Before the Soldering Iron was added, your first EBF always had one maintenance problem, which means to start it up for the first time required three LV Energy Hatches fed by five LV Generators. This is because the one maintenance problem increased the EU/t of the recipe, not its time to finish.
I can also cite the source code: in
GT_MetaTileEntity_MultiBlockBase.onPostTick, the mEfficiency stat is computed from the machine's repair status (and the efficiency provided by turbine rotors, which we'll ignore for the moment). A fully repaired machine has 10,000 efficiency; with one problem, 9,000 efficiency, and so on. Later, in
GT_MetaTileEntity_MultiBlockBase.onRunningTick, the mEfficiency stat is used to compute the machine's EU/t. The recipe's EU/t is multiplied by 10,000 and then divided by the mEfficiency stat. A fully repaired machine thus uses 10/10 of the recipe's EU/t; with one problem, it uses 10/9 of the EU/t, or an 11.1% increase. Two problems, 10/8, or a 25% increase. The effect is that each further problem increases EU/t by even more than the last one.