A "prefetching" SSE App for Windows can be found on the Power User's Apps page.
This App features the prefetching code of the previous Linux and MacOS Apps. It should be rather fast.
However I found the graphics not coming up properly every time, but couldn't deterministically reproduce the problem. It would actually be nice if someone has a machine that shows this problem somewhat reliably. My current guess is that it requires a "shared user" installation.
It will badly crash on non-SSE machines.
With the larger variety of Apps it had gotten harder to write an app_info.xml that satisfies everyone's needs. The one in this package contains the following tags and should allow smooth migration for tasks assigned to these versions:
415
425
426
432
436
You should take a look into the file before installing the App (i.e. restarting the client) if your version is not listed here.
Only run this if you're sure of what you're doing
Happy crunching!
BM
BM

Windows S5R3 SSE power App 4.36 available
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I see. For the bug report: there must be a "key" the BOINC core client writes into the "boinc init data" that tells the the graphics app where to find the shared memory segment with the progress information. Looks like this is broken (or at least different) in the 6.1.8 core client.
BM
BM