7D Lags Between Pictures

[adkspr]

During the last wedding I was shooting, my 7D was giving me some trouble--I was experiencing about a 5-7 second lag time between pictures. It was awkward because while it was lagging, I'd have to switch to my other camera to get the shot to keep things flowing, and so I didn't miss anything. 
I'm using a UDMA 400x Professional Memory Card, and I have four of them, so I wasn't working with a card that was full, or even close to full, for that matter. The cards I'm using got rave reviews from photographers with the same type of camera, but could it be the writing speed? 

What can cause this lag, and what should I do to prevent it? I have another wedding on Saturday, and I want to prevent this from happening again! 

Thanks for the help! 

[anubabs]

Hey adkspr,

I had faced a smilar problem some time back but the solution was something very simple and an oversight from me. so I don't know whether it would help in your case but here goes. I had a battery pack mounted on the camera at that time and it was also at 'ON' mode. But I was using the camera buttons at that time and the camera was showing a lag cause I guess there was a conflict between the two modes. I don't know if you were using a battery pack at that time or not but I hope it helps...