Ofcourse it will be crowded as local expatriates prefer this time for Umra as schools have a short break after exams.But you can choose your tawaaf timings wisely-after Tahajjud,Fajr or after Zuhr on weekdays.This my practical experience.Anyhow there is always enough room for everyone to pray in this holy place.May Allah accept your prayers.Remember us,all Muslims in your duas.