What is your block size (job settings, Advanced, Storage, Storage Optimization)? In v8 we found cranking that up to Local Target 16+TB (largest block size) made a massive improvement on restores from a dedupe device. Compression off but inline dedupe on (you're only moving around the dedupe but the end device still finds some to do). I think they've made some improvements in v9 but we never went back to turn that down to confirm - it's always been working so we continue to leave well enough alone for now.
Veeam B&R v9
Dell TL2000 via PE430 (SAS)