Well, thanks for your comments, I think this is great for discussions, and maybe there are some better solutions. If so, I'd like to know, just post it here.
If values types comes to Java one day, the BlockPos class may be a good solution. But for now, minecraft original sources (1.8.3) are build against java 1.7.0_55 (currently we've got 1.8 ), and I wonder when the performance boost could come.
May it be that new Date() is bad for time measures, but I could also play much smoother after changing. And this is what I want to reach - make minecraft 1.8 playable again without lags. That was my intension, and waiting for a better release in the future is no solution for me.
About the vm: I'm using oracle java 1.8.0_31, and if this would be as smart as mentioned, why can I still see this big performance differences? Using an int[] instead of a new class is really faster, this is a fact.
Next topic: the optifine people. I didn't know about disagreements with them, their changes to minecraft have made really great performance boosts on old versions, and I think that their opinion should at least be heard. I wouldn't be able to do what they did.
@LexManos: if you still have found a better solution, where can I find it to try it out? Maybe it gives me the performance boost on my computer to make minecraft smooth again.
Well, if forge rejects to do something into this direction, any other project could do so. The time of minecraft's public boost seems to be over since Microsoft built it, but if it could become playable again (currently, in 1.8.3 native it isn't), I suppose it to be interesting again. Whatever Microsoft will do with the game, if they publish a new version, people will look at performance and mod compatibilities first - and this is why forge should care about such performance things.
Just my opinions, but I'm open for yours.
Regards