Down sampling an existing projects


I’m running into CPU overloading on some songs and so, I would like to down sample existing projects from 96 to 48kHz. Projects have many time and tempo changes, and average around 60 tracks.
Any thoughts on the best way to do this?


Can you not freeze what you can, or do some bouncing with heavy plugin tracks?
Going from 96 to 48 will really change the entire sound of the mix…