1. summon 4,096 item_display. (Actual Passengers count: 4,095)
2. Try running the following command.

execute as @e[type=item_display] run ride @s mount @e[limit=1,type=minecraft:item_display]

-> As you can see in the image, the performance is greatly reduced. In addition, There was also a decrease in FPS.
These MSPT and FPS reductions disappear once all passengers are dismounted.

execute as @e[type=item_display] run ride @s dismount

When we doubled the number of passengers, MSPT and FPS degraded to unplayable levels.