URGENT. BOOKING CALENDAR WAYYY TO SLOW TO LOAD

God afternoon guys,
Last week I had a problem with my calendar taking more than 10 minutes!! to load.
Milan tried to add some code to fix the problem but it didn't work and he referred me to secondary staff which would take longer.
Unfortunately now clients are starting to complain that they abandon trying to book an appointment because the page refuses to load! WE NEED TO FIX THIS PROBLEM IMMEDIATELY before more clients lose patients.
As well today even though all break hours are registered and usually show, a client called to tell me that today the whole day was wide open with no reservations :0!! I went in to check and low and behold he was right despite all of the break hours still being there. I resaved the page and they showed back up again. WHAT IS GOING ON!!
WE NEED THIS FIXED A.S. A. P. guys....please!
Thanks as always ,
Kevin