in the attached example you can define the number of elements to display in the autocomplete dropdown
opening the initial list is quite fast
after typing a character the initial dropdown comboitems are replaced by a filtered set
this replacing takes roughly quadratically longer when increasing the number of elements in the dropdown
1000 ~ 2 sec
2000 ~ 8 sec
4000 ~ 32 sec

in the attached profiling screenshots you can see that most time is spent in the shadow sync calculations (each element removed, seems to sync the shadow)