I also prefer to view >24 hours in the grid. I understand that I can see all the prime time shows in another tab; but there are times that I want to browse the grid and see what’s coming in the next few days and schedule the recordings right there, which is something I used to do on the Windows Media Center. If performance is the issue, then maybe default to 24 hr display and have a button on the grid page with the option to show extended listing.
FYI, a feature request has already been submitted back in October: Extend Live TV Grid data to > 1 day