Describe in detail:
If you're using burst mode, do you have 3 images per second (at least) for some time and after some time the rate drops to 1-2 images per second.
or
do you start with 1-2 images per second?
Please give the full name specification of your camera. "Rebel" is just a common describer for a whole lot of cameras and there are some differences between them.
Please specify card manufacturer and speed specification. If unable, shoot a photo of the lable.
Please confirm exposure time. I think you mean 1/60 s.
Try to shot without flash. Any differences?
Ciao, Walter