Thx for reply 
It seems that this number is some inner setting becouse i dont have a killer performace problem with them and i can’t get bigger amount of particles even in preview window. The heart of the issue is that I would really love to use sub uv’s. I have 64 different maps for them packed nicely in 8 by 8 matrix on the texture. Having 64 separate textures not only seams like a lot of cliking, it probably wouldn’t be performance friendly either. And it would require 64 emiters in the particle system. Technically I could just place 10 particle system in one place and I would get myself to around 9000-10000 particles I need, but it all seems like some really unnecessary work around.