c# - HttpRequest.GetResponse() taking too much time -

i have outlook addin application i'm connecting salesforce. i'm trying request data sf api returns result in less 1 second, code takes 5-15 seconds complete.

i have tried set proxy null.

here code:

    system.net.servicepointmanager.securityprotocol = system.net.securityprotocoltype.tls12;     system.net.webrequest req = system.net.webrequest.create(uri);     if (includecustomheader == true)     {         req.headers.add("authorization: oauth " + servicemanager.token.access_token);         req.headers.add("x-prettyprint:1");         req.contenttype = "application/json";     }     else     {         req.contenttype = "application/x-www-form-urlencoded";     }     req.method = "post";     req.proxy = null;      byte[] data = system.text.encoding.ascii.getbytes(payload);     req.contentlength = data.length;     using (var responsestream = req.getrequeststream())     {         responsestream.write(data, 0, data.length);     }       //here it's taking 5-15 seconds, each request gets batch of 200 records     using (var response = req.getresponse())     {         return new system.io.streamreader(response.getresponsestream()).readtoend();     } 

don't know missing , or there other reason? suggestions?