regarding slow network

Hi,
In our organization we are using a file server and a local intranet server. this file server is connected to the local intranet server. we need to access the file server frequently for updation, file transfer etc. but nowadays our network is very slow. i don’t know what to do. We are using “Net Gear manageable switches”. regarding cabling there is no problem. so please can anyone help me in this issue.

Thanks in advance.