[IDC] Look into cornerstone request issues

[JamesAPetts]

There appears to be some issues with how prefetching works:

Yes, there is definitely something wrong with the frame fetching behavior. If possible, I'd prefer to fix the underlying issue, since 280 slices is not an unusual case.

Here's what I see:

open the console to the Network tab
open the study url https://dev-viewer.canceridc.dev/viewer/1.3.6.1.4.1.14519.5.2.1.6279.6001.224985459390356936417021464571
grab the slice scroll tab on the right side and pull it to the bottom of the window to look at slice 280.

The result is a very long (~5 second) delay with the "Loading" message before the slice appears even though the network tab is very active.

At the beginning, slices are downloading within about 100ms, so if things were working correctly I should be able to see the any interactively selected slice within 100ms.

But instead it appears that as queue is being swamped with fetches related to slices that were triggered as I scrolled past, and they are not canceled even though I'm no longer on that slice. In the end so many slice fetches are queued up that some of the accesses take over 7 seconds.

We should look into this.