Switch to tea. Coffee is a markedly inferior stimulant and the only reason Americans drink as much as they do is because of a certain political skirmish over taxation.

Tea contains L-theanine, which acts synergistically with caffeine. It increases levels of dopamine as caffeine does, but also levels of GABA, helping to reduce stress and take away the jittery, distractible edge that comes with coffee drinking. If you were to sit down and design a drug to help with mentally taxing work, you'd be hard pressed to concoct something better than tea.