Following both the tables having no rows (data) with same table structure with different name (table1 and table2), even table1 taking lesser time to show the result than table2 two. Why?
Select count(1) from table1;
Select count(1) from table2;
Is it possible?
Yes, it is possible.
If you populate table1 with many rows (10 million or above) and then delete all rows (be sure to make DELETE not TRUNCATE) and make TRUNCATE on TABLE2 then response time will be different even both tables contains no data. For TABLE1 all empty blocks must be read, while TABLE2 contains only 1 block to read. Read about High Water Mark for details.