My understanding, from reading about this online over the past few months, is that for smaller, lighter, single-motor O Gauge locomotives, an OO Gauge controller will suffice.
For larger, heavier, twin-motor locomotives, a “smart” booster is required.
For example, an NCE PowerCab plus an NCE SB5.
Getting a locomotive moving takes more energy than keeping it moving, so how you operate your layout will affect consumption, too.