Operating profits at the Insomnia coffee chain grew to €4m last year.
The figure compares with €848,000 the year before, when the business was hit by almost €3.4m in exceptional costs.
Insomnia's revenue last year was €30.9m, which compared with €28.7m the year before, according to accounts filed for its parent firm, BHJ Holdings.
Of its turnover last year, €28.5m was generated in Ireland, with the remainder coming from the UK. The company employs about 440 people.