I have also observed delay in retrieving data, When getting data from google Finance is more slow than NSE india site. I am trying with Excel VBA which suddenly crashes while pulling data from website is a common setback.
I do not know Data pulling is legal or illegal…
Since real time data is really costly affair, its generally used by FIIs, DIIs and brokers as Nitin sir said in his video, other option is to get APK Licensed key for website data from Broker, as some members are getting data by paying monthly nominal fees, this was also said by sir in one of his videos.
let us design a profitable system, test for 1 market cycle and keep looking for better options…
Hope this information may help you in decision making.
If anyone who can suggest better option is welcome..