One other less common thing that can cause receivers to bog down, particularly with respect to taking commands. This has happened to me 2 or 3 times. Basically if some
remote control in your collection goes beserk and starts sending all the time, it can make your equipment seem to go beserk too. One time, I accidently spilled a bit of soft drink on one of my remotes, then I couldn't get one of my receivers to work at all, wouldn't respond to it's remote, and I don't think it was even the remote that I spilled the drink on. Took me a while to figure out that this remote that was just sitting on a table was messing things up. Another time, I put several remotes down on a table, and placed some remotes on top of other remotes, and the weight of the additional remote made the ones underneith start to send continuously. Yet another time, I put several remotes in a drawer, and closed the drawer, which pushed some of the buttons on some of the remotes. I think one of these last two was what caused my TV to go into the 45 second response mode (and stay that way even after I stopped the remotes from sending, until I unplugged it). Generally, the only way I noticed that remotes were sending continuously is that I have one of those RS Pyramid remote extenders, and it blinks when it sees IR remote signals, and I just happen to look at it and noticed it blinking continuously.
Another thing, is that I have noticed that one of my Fortec receivers seems to be confused by either the light or electrical interference that comes from computer screens. I had to move the Fortec to an orientation where it wasn't facing a computer. Also, my RS Pryamid remote extender seems to react to computer screens. One time I found that I could get it sending by just moving my mouse over one particular window of one program I use a lot. Also, one of my receivers stopped responding to remotes in the afternoon when sunlight came in a window and hit the receiver.
Anyway, interferrence from stray light or malfunctioning remotes can be an issue, because the CPU bogs down spending all it's time processing IR signals. To find out, you might block the IR sensor on the receiver so that it can only see it's own remote. And you'd be surprised that it isn't easy to block the IR. I have some receivers that I needed to block the IR sensors while programming another similar receiver, and I found that I needed like 4 layers of dark construction paper to block the IR signals. Any less, and the IR would go through to the receiver.