Direct Lake Performance vs High Cardinality

Hi! I'm currently working on optimizing our semantic model, which is consumed through Direct Lake, but I'm hitting a wall in terms of performance. The model is composite (Direct Lake + Import), based on Direct Lake + Import approach (our beloved https://www.sqlbi.com/blog/marco/2025/05/13/direct-lake-vs-import-vs-direct-lakeimport-fabric-semantic-models-may-2025/ ), where the dimensions are imported and the fact table is on Direct Lake. The fact table itself contains more than 300 million rows and is growing fast. Unfortunately, it has very high cardinality, with around 90% of the values being