FPS Boost is a feature that is exclusive to the Xbox Series consoles allowing them to push older games to run at a higher frame rate.
Jason Ronald, Director of Program Management at Xbox has suggested that while their support for enhanced backward compatibility has ended, they might return to it someday if they can find out a method to enhance it further.
“For those asking for clarification, we knew that our current FPS Boost techniques would only work on select titles. This is similar to resolution enhancements for Xbox One X. We have enabled FPS Boost on 130+ titles, but we have tried many, many more unsuccessfully, ” said Jason Ronald.
“Enhancing games from the past is difficult as we don’t make any actual changes to the game’s source code itself. If we are able to develop new methods to further enhance backwards compatible titles we will pursue them, but we don’t have anything on the immediate horizon.”
Based on what Jason has suggested here, Microsoft might add more games to the FPS Boost/Resolution Boost list, but the caveat here is that they need to find a method that is better than their current solution. Obviously, there is no indication they have found one so far, but they did try the current FPS Boost implementation on numerous games, some of which worked out successfully while others failed the enhancement.
It could be logical to assume that a game that we might demand enhancements for has already been tested but perhaps it just didn’t work out in the end and Microsoft didn’t implement it for their program.