So what you could try is to initialize sIFR inside a dom ready event. This way, sIFR will be initialized before "onLoad".. this should solve your problem.
This is how you could implement it using jQuery. The following code should be placed in the <head> of your template
Using jQuery just for the DOM ready event is admittedly a bit overkill, but I'd give it a try just to see if it works. Another thing to try (without the use of jQuery) would be to place the following code just before the closing </body> tag!