DVR Cable Box changes channels VERY slow

[CyinCo]

I have mediacom. Sometime in the past couple months, my DVR cable box starting changing channels very slowly. There is just a black screen that holds on the TV for nearly 5-10 seconds before the channel will change. My non-DVR HD box changes channels instantly.

Does anyone else have this issue? Could my DVR tuner be going bad? It didn't used to behave this way.

Thanks.