My free DB is faster than my M20 DB?

NodeJS Application
AWS us-east-1
Same server and application, only different was swapping between free mongodb and m20 dedicaated.

I’ve been developing an app on MongoAtlas free version for many months now. I’m at a point to do stress testing using Jmeter.

Situation:
I ran some Jmeter tests against the free mongo atlas db to have base metrics.
I excitedly purchased a M20 in us-east-1.
I pointed my API to the new M20 DB.
Results were 2-3x slower in terms of throughput, triple deviation and average was 3-4x higher whilst using the m20 dedicated.
I ran the tests 3x on free and 3x on m20 dedicated to maybe see if it was a fluke. results remain consistent. and mongo support isn’t much help thus far.

Anyone experience this?