How long will lingering side effects last. after taking xanax (alprazolam) i did a fast taper and want this b over next friday can not come soon enuf?

Depends: First of all you did a good thing by stopping xanax (alprazolam). Drugs like this shouldn't be taken on a regular basis except in certain circumstances. Benzodiazepines can cause dependence, tolerance and withdrawal, and can interfere with sleep quality. The length and severity of withdrawal depends on the amount of time you were taking the drug and the dose. Be patient you should eventually feel better.