[MISC]
I think the main problem was the dreamworld update, it definitely changed the way the engine recognizes the surroundings, especially npcs. Even if you tick all you can in the options for preloading, it seems to load a lot in the background, too.
Before dreamworld i could clearly and honestly state, that my win7 pc went smoother and more stable than my winXP pc....now it gets different with each patch
About the reason, it will be hard to judge as player, since funcom is unable to properly do update notes and just pop out the "improved and done minor tweaks and fixes" sentence for ALL they do technically
On Win XP, one source of crashing was music enabled during loading. It was either crash to desktop or just froze at some point.
Disabling music almost made crashing on loadscreen disappear for me.
I play now completely without music (a shame) and the last patches rather improved things than hurt (on both systems).
Another thing is the amount of relogging and instance travelling (the different cultures seem to have different resource bases, e.g. a lot of travel from stygia to cimmeria is worse than a lot of travels inside Stygia). Still, the longer i play the more unstable the game gets memorywise...it got better, but still is there.