Unresolved

I'm much slower on straight

In which case it is most likely you didn't get DRS throughout the race and this theory is supported by the fact your car was in second place for nearly the entire race and more than a second behind the leader at the start / finish line.

Even if you did get DRS your low level tech centre would mean it is not very powerful.

This combined with the fact that you just switched leagues and joined your new league part way through the season (race 8) so your design will be very low.

OK, my mistake about joining but I still think DRS (or the lack of it) may be the reason your top speed was lower than some of your competitors in USA.

In today's Abu Dhabi race you had one of the highest top speeds in the Rookie tier. Presumably today you got DRS whereas in the American race you didn't.