Surfactant molecules are tested as water-in-crude emulsion breakers to attain the quickest separation rate in the so-called "proportional regime". A concept of demulsifier performance is proposed on the basis of the required demulsifier concentration to offset the effect of a given amount of asphaltenes. The experimental evidence allows one to rank the tested products and relate their performance to their hydrophilicity and molecular weight. Some evidence indicates that the presence of acids in the crude makes it easier to break emulsions and suggests that so-called "extended surfactants" can significantly shorten the demulsifying process.