search speed

[2ne1Abcd]

I have two server ( server A & server B , which server B is LDAP server , there are over 700,000 records in it  ) , in everyday , server A will run a script to do the search in LDAP server then update it  , as there are many records in it , once the searching is started , server B nearly hang .

It must perform thorough record searaching , no searching criteria can be change , therefore , I would like to ask if there is any method may reduce the affect to the server performance of server B  when searching?

thanks