This is a current limitation of the physics engine. See issue https://github.com/microsoft/pxt-arcade/issues/1057
Is there still a maximum speed, what is it? How is that applied to an accelerating object?
There is still a max speed, but it’s much higher now and we can change it if people feel it is still too slow. @jwunderl any chance we could get a TS API for changing it?
Yup, max speed is currently 500 in each direction by default. It’s easy to add an api for changing it (it’s currently a parameter on the PhysicsEngine constructor, but there shouldn’t be any risk to making it adjustable without creating a new one as it’s only used at the beginning of the movement during physics.) The new physics post I made when we updated to include it has more info / an example of how you can change it for now: New Sprite Physics in beta!
Edit: Wrote up a bit more reasonable ts api: https://github.com/microsoft/pxt-common-packages/pull/974