Why has my 550D camera buffer decreased?

Question

Normally I can shoot 9 JPEG's into the buffer. This amount is indicated by the number in the lower right of the viewfinder, next to the focus confirmation light. Now that number says 2. And indeed, if I shoot more than two JPEG frames subsequently, the camera will hang to write to the SD card and then will proceed shooting further.
This behaviour is independent of SD card speed, JPEG size or quality, or shooting mode.
When I switch to RAW I can shoot 4 frames in a row.

It seems that my camera buffer is partially filled, but I can't find out how to empty it.

Answer 1

As found on page 220 of the manual, the maximum burst rate can be altered by custom functions for noise reduction set to on. Also, this would explain why in RAW mode you do not experience this, as the noise reduction is probably not applicable to that shooting format.

I would suggest going into your custom functions and disabling High ISO Speed Noise Reduction. You could also do this by resetting the camera if you don't want to find the setting.