As I said before (unless it is a very basic keyboard) registry memory is the answer and you don't need a laptop at all.
You are absolutely right, during a performance you have to switch in a second and be ready for the next song/number or you KILL you own show. Every performer knows that (or should know) especially when you are playing for a crowd on the dancefloor.
As I don't know the keyboard that is used, in general the registry-memory is a series of buttons. Under each button you can store a complete setup for a song.
How does that work:
At home you set up the keyboard for a certain song, meaning all the voices, drum, effects etc etc. In short everything that is used for that song.
This complete setup can be stored under a registry-memory-button.
Next you program the setup for another song and save that in memory under another registry button,
This you can do for the amount of registry buttons available. Let's say there are 8 what is quite normal on a midrange keyboard and it is usually called a BANK.
This bank you save in the keyboard under a name let's called it OLDIES.
Now you can do the same procedure again and save this bank under the name BIGBAND or whatever.
You can repeat this as long as there are BANKS available in the keyboards memory. A bit of a keyboard has about 96 BANKS meaning in this example, you can store in memory 96 x 8 COMPLETE song setups.
NO band in the world needs that many for one performance.
Now, during the performance the only thing you have to do is LOAD a bank, let's say bank OLDIES press one of the 8 buttons and the keyboard is in a split second ready for the song under that knob.
Finished the song? Just press anther button and you are ready for THAT song.
Done all 8 songs, load another bank (that takes a second!), like BigBand and the keyboard is ready for another 8 songs.
I hope I made it a bit clear.
Regards
DickR
(retired Dutchman and film-sound-engineer)