Ok, then why does it have so much gc to do? Is it all in your code? Then maybe you have too much variables and objects which get create every frame, so try to move every object create out of for loops when possible a,d reuse objects and thus avoid creating objects. Or (in an extreme case) have a more global approach and move such variables which you need every frame to a separate class or as field and use them, instead of recreating them every frame.
Also, in the docs there's a section
BTW, only 1ms can't be that big a deal can it? And if it is, maybe you are asking too much from the hardware.