When using setTimeout as a way to go about updating the text that is displayed in a title tag, the time at which frames will run can change depending on the browser. For example if I set 33 milliseconds as the desired target time at which the next call to my loop will run, I often get a time around that much if the tag is active and I am not doing much of anything in the function call. However if I change tabs the time between calls will increase to 1000 milliseconds regardless of what value I set.
For example something like this:
Will update the title text to the amount of time between function calls, as expected it will give me around 33ms if the window is active, but will increase to a second if the window is inactive.