This all depends on whether you are a man or a woman. The conflict resolution strategies causes them to react in different ways.

Women during a experiment improved in stressful meetings using caffeine. This was because they tended to have a conflict resolution style that is more collaborative.

Men in the experiment tended to do worse after using caffeine. This was because their fight or flight response was active. Caffeine enhanced this and made it harder to think.

In short, if you are a woman then drink coffee before your meeting. If you are a man, don’t.

Citation: St. Claire, L., Hayward, R., and Rogers, P. “Interactive Effects of Caffeine Consumption and Stressful Circumstances on Components of Stress: Caffeine Makes Men Less, But Women More Effective as Partners Under Stress.” Journal of Applied Social Psychology, Volume 40, Issue 12 December 2010 Pages 3106–3129