I think that about sums it up.
There is support for this argument: If you have experience with DISH DVRs, they are generally all pretty snappy. Of course the trade-off there is they are also unreliable, and the DISH service is somewhat inferior in many ways (there are still top-market stations that are not in HD LIL, for one thing). So their coders have the skill to provide the speed, but lack the skill to make their DVRs very reliable. And all DVRs pretty much run on the same garden-variety off-the-shelf CPUs and decoder chips from the same sources, so that can't be used as any excuse.
I have to agree with Halo. My HR10-250 is much faster than my HR21-700s which have a processor that is 4 or 5 times faster than the HR10. The code for the HR10 was written by TiVo. They knew what they were doing.
Well, yes, in some ways it is faster, and Tivo made efforts to speed things up in some of their up revs as well, but at the expense of reliability, so maybe no coder has the chops to do both.
And the HR10, much-beloved as it is, is not really all that fast in many areas, although I agree it is faster in GUI response for many of the most frequent tasks. I just deleted a SP on my one remaining HR10 yesterday (out of a total of only 9 SPs), and it took over 4 minutes to recover. More than 4 entire minutes
of the "please wait" clockface logo staring back at me. It also takes 30-40 seconds to display the main GUI screen when I first access it each day, but this is likely due to the fact that it has to first parse failed mothership connection attempts for the last 1800 days.