Newsletter emails sending rate drastically decreases after moving EC2 and RDS servers

We have been using AWS services in the North Virginia region for some years now. As most of our customers are in Asia, we wanted to move our servers to the Singapore region for lower latency. We moved our EC2 and RDS servers to Singapore and it resulted in lower latency. However, SES endpoint was still North Virginia (as there is no endpoint in Singapore). Once we did this, we noticed that the time taken to send our newsletter emails reduced drastically (from 12000 emails/hour when EC2/RDS were on North Virginia to 2000 emails/hour when EC2/RDS were moved to Singapore).

1) Is this decrease in email sending speed expected if SES endpoint is North Virginia and EC2/RDS are in Singapore?

2) If yes, is there any solution by which we can continue to have EC2/RDS in Singapore and still send our emails at a fast rate?

Any help would be much appreciated.

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