It should work with dual core too, just get the core numbers right.
I remember this exact thing happening with WoW, (which is also not optimised for multiple cores) and there's a way to edit a config file to make the game load onto one core. When I get home from work I'm going to look at the config file and see if there is a way to mimic the same with swtor's config.ini file. I'll report back in about an hour
Thanks for this reminder will have to go to a co-worker of mine who reminded me of it. Both ways may work, but I would expect that a change to the config file would be the better way to do it, as changes to the launcher or shortcut might (_MIGHT_) get removed after a patch (though they shouldn't) while config files definitely shouldn't unless it's an expansion or something mega.
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Just did more Googling, and what WoW had was a way of getting the game to run when you had quad core
and so on, so there's probably a way to force the game to THINK you only have a single core, and thus force it to behave as such.