the booking calendar is very slow to load

I am not sure if there is a problem with the calendar or not but before checking with you guys, I checked with my host. This is what they replied:" It took about a minute for the calendar to load after selecting your name. Both the webserver and database server loads are low, we are not sure what could cause this problem. Please check on the calendar plugin to see if there may be anything a miss."
I have several clients who tried to book an appointment with me(kevin) and the schedule to an abnormally long time to load. Could it be a problem with the calendar plugin?
If you go to my website http://www.simplyfitcanada.com under the calendar, if you select as the trainer myself kevin and leave the default 60 minute training the page hangs and just shows the word BOOKING CALENDAR with no actual calendar that appears for quite some time. What do you think the problem is?
Thanks,
Kevin Frost