I am advised by the Irish Naturalisation and Immigration Service (INIS) of my Department that student visa applications are generally processed within 8 weeks from the date on which the application is lodged at the Visa Office/Embassy/Consulate.
Processing times can vary over the year and between countries due to volumes received. In addition, some applications may take longer to process where particular issues arise in individual applications or if all the necessary supporting documentation has not been submitted or the supporting documentation requires verification.