database managment problem

Question

i am developing database driven application .net platform,
performance issues does not arrives when der is not much load of data.
in live projects, der can be thousand of records in database.
frequentlyin my application there are some tables which will required lot of DML operations, but a perfomance issue arrives when there are of thousand of records

guys pls help me out, how can i overcome this problem

i mean, i should maintain several backups, or copy database to another location
or any such other method

lf possible pls provide brief details any of the method

thanks in advance