ps #6: is there a reliable solution to track respone times (latency) over time? I want to enter, say, 10 urls, preferably some with a cookie (loggedin), and see

ps #6: is there a reliable solution to track respone times (latency) over time? I want to enter, say, 10 urls, preferably some with a cookie (loggedin), and see from various locations how fast they are (including js, images, ...). I'd pay 10$/month for this. I don't need any other features, just good, easy and reliable latency/speed measuring, so that I can work on improving it and actually see results (or not).