This doesn't fix the problem you are describing about lag between switching channels in general, but there's a better solution for the 'watching 2 games' use case.You can't really instantly flip channels back and forth real quick if you are switching between 2 ball games or something, the channels take a good 2-5 seconds to appear and start working when you change a channel.
Press down, it will say you're about to start Double Play. Press it again, the channel will change... now go to the second game. Press down to flip back and forth to see both games much quicker because the tuner isn't changing channels, you're just switching tuners. The 'previous channel' buffer is unique to each tuner you are watching too, so on Sundays I'd be watching the Chiefs on one and red zone or another game on the other.
Genie has picture in picture. It's pretty nice on a big screen, and just use down to swap back and forth.