1) 5-7 seconds is a lot, so this is no ddos attack. Many commercial companies that parse sites(including MVideo, ozone and other shops) just parse one item in 5-7 seconds.
Is there for example a possibility as once open the site and continuously read information from it, not to establish a connection every 5 seconds?
Is, unless the website gives information on the websocket(not encrypted).
3) Or to load a page every 5-7 seconds, or you can look in devtools, maybe the site gives info using xhr request. In this case, it may be easier to parse.