Alright, I tried things out a little more this morning to confirm the changes I observed last night weren't just in my head. Roderick, changing the CPU, and GPU que size made no significant difference in channel changing as you suggested. I investigated this after your suggestion, and I observed it for myself by turning them almost all of the way up, and then back down which produced no noticeable changes. Changing the quality preset also didn't do much for me. I tried the strongest and weakest setting, and there wasn't much difference.
When I tested last night I strictly used the mini guide to change channels. MC took about four seconds to change channels, and I'm still getting about four seconds for each channel change today using the mini guide. Where there is still an issue is backing out to the guide in theater view, and changing channels from that. With both ROHQ and standard, channel changes are almost twice as long, and it seems to take an extra second or two with ROHQ. I still get the windows loading circle as well, even without steam (So that is debunked also). Roderick, in a different thread I believe you said you aren't experiencing any issues when changing channels from the guide. I think I'm the only person on this thread with an AMD card so I suppose I'll throw my NVidea card in here and see what happens.
About steam, etc. Steam wasn't the only application I removed as I also took off the xbox console companion, xbox smart glass, and a few other applications. When I'm done poking around with it steam will have to come back anyway but I wanted to remove as many applications as I could to narrow down any performance issues I might have to MC.