Hey Pieter,
Sorry you’re running into this.
You may want to try a simple fix that is to edit your connection, head into Display settings and switch from “High quality” to “Good performance” (or lower the color depth). Then, in Advanced, turn off GPU hardware acceleration. That way the app won’t try to push too much through the iPad’s GPU pipeline and suddenly everything feels snappier.
If you still notice hiccups, try flipping on Touch mode instead of Pointer mode-using direct touch gestures tends to bypass the extra pointer smoothing that introduces lag. Lastly, double-check you’re on the very latest RDP client in the App Store.
I hope this helps.
Finn