You'r probably doing some other operations unless adding only one item to a combo doesn't take too much time (actually it doesn't make sense adding one item taking 1.3 seconds).
My advice is :
- Create another class having one combobox .
Add item(s) to the combobox and see how much time it takes.
long empieza = 0; long duracion = 0; empieza = System.currentTimeMillis(); cbxUnidad.addItem("TODOS"); duracion = (System.currentTimeMillis() - empieza); java.text.NumberFormat nf = new java.text.DecimalFormat("#0.00000"); String totalTime = nf.format(totalTime/1000d); System.out.println("Adding the item TODOS last " + totalTime+ " seconds");