I can't really say anything about your RAM issue, but count(*) is always a bad idea if it can be avoided. Assuming you have a primary key on the table, do a count(pk). In my experience that alone cuts down up to 30% of execution time.
i want exact count so am doing this...
But as you are saying it is not doing so, at first without primary key i had a column "id", it took the same 3 seconds to show the count, after reading some tips i created primary key on that "id", and i did select count(id) from table, and now also it is taking the same 3 seconds.
