> may be you can give me some Idea to manage server datbase (like datapages pages,cahce,sweep). database server slowdown when compluter client running many application,

No way. You must find out exactly what "slowdown" is and it's reason.
Server can't just "slow down", there must be slowly executed queries.
May be they come to bad plan, may be they cause garbage collection - no
way to find it out via telepathy. You must use tools, such as IBAnalyst,
IBTransaction Monitor and FBScanner by ib-aid to find out what is wrong
and fix it. There are many things that can be wrong: from hardware
settings to DB and application design.

SY, SD.

PS: Look at the situation from different angle: you want us to solve
your problem for free to get your money from your customer. It is...
boldly, isn't it?..