Field type select unresponsive with big data

Hello I have a form with 2 field type select.
The first field name DEPARTMENT lookup into table DEPARTMENT with only 4 rows
The second field named PARTS lookup into table PARTS with 2000 rows.
When selecting an item in field DEPARTMENT it works fine. But when selecting an item in field PARTS the page becomes unresponsive and take time to load the list.
Is the their a way to fix that issue?