Check your refresh rate. With my 4k TV, the mouse gets laggy if it falls back to 30hz. I plug my TV directly into my laptop with a USBC -> HDMI cable. Docking

Check your refresh rate. With my 4k TV, the mouse gets laggy if it falls back to 30hz. I plug my TV directly into my laptop with a USBC -> HDMI cable. Docking stations often fall back to lower refresh rates.