表格设计错误或者在制作表格时选择索引错误了吗？

I've build web application as a tool to eliminate unnecessary data in peoples table, this application mainly to filter all data of peoples who valid to get an election rights. At first, it wasn't a problem when the main table still had few rows, but it is really bad (6 seconds) when the table is filled with about 200K rows (really worse because the table will be up to 6 million rows).I've build web application as a tool to elimina