Greetings Space Pilot,
Sorry for the late reply.
Seems that your post got lost in the myst of threads in here
I hope the above problems are now resolved for you.
When it happens your thread is not answered after a few days (3-4 days) and if you see other threads gets answered, then you can bump your thread because it has likely been forgotten. Only under those conditions otherwise any bumping will be infracted.
Given your specs, your computer definitely should be able to handle a web-browser game such as darkorbit.
This being said keep in mind since Flash only is able to deal with a single core, if that core gets overloaded, it will result in the same behavior as if you had a single core CPU.
Lately I have noticed some browsers preforms a lot worse than others. I even got some of my computer to crash as I only was on a regular webshop using some scripts (was not DO/BP websites).
I switched to an other browser on the same website and had no issues.
What I am trying to say, is not only your computer -core- specs matters, one browser may perform better for one usage when an other one may perform better for an other one, as well as one browser could perform perfectly on one operating system, and not being working as good on an other one.
Keep in mind, because something work perfectly for someone else, does not mean that solution will work as good for you.
Best is to test all the available solutions and find what is one which works the best for you.
Always remember a single windows update/browser/flash/java update can change everything again...
Sadly that's how it is...
Hope this helps.