Temporarily, I'm down to an ancient iMac with an obsolete OS. I use Firefox, which won't stop telling me my plugins are outdated. I can't stream Netflix or Hulu, and Flashplayer won't run on Facebook. And yet, I have very few issues with the speed of this site. And on my Kindle ... no problems at all.
I can appreciate the frustration, however. When I run Photoshop, Illustrator and Firefox simultaneously, I eventually get the "rainbow wheel of doom," which continues to spin until I force-quit and reboot. No amount of cursing or desk pounding will appease the wheel. But that's another story, and slightly off-topic.
Unless I'm mistaken, recent attempts to upgrade to a faster format incited much sturm und drang. In spite of that, I believe an upgrade is inevitable.