Odd performance / buffering problem

[Jumpin Jon]

Hi all,

 

I'm experiencing a really odd performance problem with Win2K3, IIS and PHP5.  I believe all the software to be configured correctly.

 

I have various sites on this host and they all exhibit the same problem - very, very slow performance.  I'll serve up a pretty standard page - some MySQL access and a page of results from that query.  Depending on the amount of output, the problem gets worse by magnitues - a few line of output will be slow, but raise that to 10 or 100 and the problem doesn't get like 10 or 100 times worse, it'll feel more like 100 and 1000 times worse.  As an example, a page that returns 100 results will take maybe 40 seconds to arrive at the browser.

 

If I add an ob_start() at the top of the PHP scripts, however, the times drop to far more sensible times.  A page that previously took 40 seconds to load will now complete in more like 1 second.

 

Any thoughts on where the problem might be?  Working on the assumption that Windows, IIS, PHP and MySQL are all working correctly, my suspicions turn towards the networking environment of the ISP where the server is hosted.  But, I wonder what might be a feasable explanation as to why having PHP buffer large chunks of output vs. streaming the output might make a difference?

 

I'd appreciate any thoughts or feedback.

 

Thanks,

JJ