My site checks the database for overdue reminders by making an AJAX request every 5 seconds. I've been told this is not ideal because of too many AJAX calls, one person said it's almost like DDOSing your own site if there are many people on with several tabs open etc.
The alternatives are using websockets or ajax-long-pulling. I can't use websockets because my shared hosting doesn't have that capability. Ajax-long-pulling is not ideal because of limited connections.
So a workaround I thought of would be to have a file on the server which simply stores a token. The browser reads this file via a hidden i-frame every 5 seconds, and if something relevant changes in the database the token is changed and this signals the browser to send an AJAX request to get the new reminders.
Would that be a feasible workaround to significantly reduce the load on the server since it's not making so many AJAX calls every 5 seconds since it's just reading the file instead?