For those having issues with their game freezing when you mouse over something that is "active" (ie. the cursor become a cog, or you are mousing over a fire etc..)
A buddy of mine at work told many in his guild had the same issue, and they had determined that it was caused by the tooltips, so they have a macro to disable tooltips and I am told that fixed the problem for most of them.
So here's the macro. I have not tested it, but if it helps you, then my job is done.
To deactivate tooltips:
/script GameTooltip.Temphide = function() GameTooltip:Hide() end; GameTooltip:SetScript("OnShow", GameTooltip.Temphide);
To reactivate tooltips:
/script GameTooltip:SetScript("OnShow", GameTooltip.Show);