The actress' portrayal is definitely atrocious. However, the writing for her character also sucks. She doesn't do anything other than yell at Tyrion for not fucking himself over to run away with her while he tries to keep her from being too loud and getting in even more trouble

Also I'm terribly unconvinced of Tyrion's love for her (or hers for him). The whole thing, from writers/directors to actors, has just been stupid. The sooner she dies, the better