Fixed a problem of repeated crashing with a new install of Firefox 28 on Windows 8.1

Question

This isn't so much a question as a contribution of solution.
On a new computer running Windows 8.1 a new installation of Firefox 28 was repeatedly crashing or freezing ("no response"). Loading pages could be slow, and scrolling jagged. Totally unusable, especially after playing content with Shockwave.
Although I had not installed any plugins apart from Shockwave and Adobe Acrobat, I had a look and was surprised to see several that I had never asked for. I deactivated those I do not think I need:
Intel Identity Protection Technology
Photo Gallery
WildTangent Games App V2 Presence Detector.
Since deactivating these, Firefox is running fine. But I had been obliged to use another navigator for a week until finding the time to research the problem.
Why are these unasked-for and obviously (for at least one) troublesome plug-ins installed by default? It's not doing Firefox any good!

Answer 1

I return to this thread more than 3 months later, during which time I have not had a single day's satisfactory use of the latest versions of Firefox over Windows 8.1 with Flash content. Not very stable at the best of times (constant increase of memory usage) and when accessing Flash content, ffx came as near as I've ever seen an app come, to getting drunk. Memory goes through the roof, repeated freezes, disappearances/reappearances in the UI and very difficult to shut down. I've tried all the recommended fixes, disabling hardware acceleration, protected mode etc. to no avail (but a LOT of wasted time).
I've been having to use IE to access Flash content.
Last night I finally came to what, for me, is a quite radical decision to downgrade. I'm not _recommending_ this to anyone, but some may find it helpful as long as they're aware of risks and take appropriate precautions. Note that the official Mozilla archive page puts switching to a different browser _before_ returning to an older version of Ffx.
I've gone back to Ffx 28.0 dated 2014.03.15 (the Ides of March, I now note...) and Flash 10.3.183.90 which I downgraded to a bit earlier as part of my attempts to find a solution. Firefox is now stable, memory usage reasonable (currently 202MB for 6 tabs including some Flash content).
I currently have only one comment, handling of marquees (which has always been jerky in Ffx) I now see is using ''excessive processor time (up to 15% on a Core i3 with 4 GB RAM!)'' and jumps of 5-10 MB in memory usage. The latter returns to initial level at each cycle '''but I rather suspect doesn't in Ffx 31''', which might contribute to an apparent leak. [Edit : this seems all right on a different machine, so will have to find what's causing the problem on mine!]
Fortunately the cpu and memory usage disappear as soon as the marquee is pushed out of the viewport... so I conclude Firefox is not handling them if it doesn't have to show them.
Will post back with any developments but at the moment I'm staying with these versions!