Query throughput

Hi, thank for your answer. I do the query like this

{
 q(func:eq(label,"resblock"),first:10){
 uid
 ...
 r_1{
 uid
 ...
}
 r_2{
 uid
 ...
}
}
}

there is total 5 hundred thousand result. and I got 10.in first, I cost 20+ms. in second, I cost 300+ms. the latency is too different.