Yes this is a common complaint despite what some may say. I've experienced this lag as well but the hr24's are the fastest Dvrs directv has so far. overall I'm also pleased with the hr34 even with the occasional lag. Worse Dvrs I've ever used were between the hr21's-23's. My experience is limited to 10 years with dish and almost 5 years with directv so I'm sure there are much worse out there.
This is one reason why I hung on to my HR20's for so long (and the OTA tuner), the 21-23's just didn't have enough to offer to upgrade to each of them as they came out.
They could have skipped the whole series of them except they would have had NOTHING new till the H/HR24's if that was the case.