Facing a problem with a document when I am opening that document Distribution services taking 80-90% CPU , can anyone help me understanding that why is it happening.
What you are saying is technically impossible. The Distribution Service is responsible for scheduling and initiating reload jobs on your server. If you say you are opening a document, I think you mean to say that you open it in the AccessPoint and the QVS (the QlikView Server service) is allocating >80% of all cpu cores, correct?
Aside from optimizing your document as suggested by other posters, you can also exclude cpu cores from being used at all by the QVS. That may be helpful if you also do reloads on the same machine. And you should always exclude a single core for Windows, or in some cases you won't be able to even open an RDP session or do anything else on your server.
Have a look at QMC->System->Setup->QlikView Servers->Your QlikView Server->Performance->CPU->CPU Affinity
