Internet Explorer (IE8,IE9) slow page load due to Flash and ONSPEED sliprt.dll

Client complained about slow internet page loads. They use Windows Vista and Internet Explorer 8 and to date it had been fine. When I looked at the problem it was just like the browser was stalled trying to connect to a down host. It would take minutes to load a page and was basically unusable. Very frustrating because Opera and Firefox both worked fine.

I got them working temporarily on Opera and arranged to pick up the laptop when they went on holiday for a few days. Back at base I tried a few things which did not work

  • IE8 -> IE9 upgrade
  • IE9 -> IE8 downgrade (uninstall IE9)
  • ONSpeed uninstall and re-install

and then I just got the feeling that flash was a problem. I downloaded the flash installer (which is a downloader not the full application) and tried to run this.

I got an error message about sliprt.dll was not found e.g. This program can’t start because sliprt.dll is missing from your computer.  Try reinstalling the program to fix this problem. The sliprt.dll is part of the Slipstream which is used by ONSPEED. This is HTTP cache/accelerator. The dll does exist in \Windows so obviously some other problem and the error message is due to a missing program call.

I then downloaded the full flash install file ( see ) for both Internet Explorer and for “Other Browsers”.

These ran OK and installed without error. This cleared my Internet Explorer stalling and running slow problem and now IE8 is working fine. I upgraded to IE9 and that is also working fine. I was also able to upgrade to Windows 7 Home Premium (using upgrade disk) and the laptop remained stable.

May not work for you but it fixed my client problem.