4 year old had turned into a problem child in the last few weeks. HELP

So, we have two kids. A just turned 4 year old girl and an almost 1 year old daughter. My 4 year old has been, by all accounts, a pretty easy kid. Normal tantrum stuff but nothing where I was seriously worried about her behavior. Over the last month or so, she has turned into, for lack of better words, a demon. She is rude, bossy, disrespectful, and basically down right mean at times. Time outs and talks after used to work pretty well to curb her behavior but nothing seems to effect her at the point. She laughs in the face of punishments and I actually feel like she is full on mocking me when I try to redirect her and then explain why we can’t be disrespectful little assholes all the time. I spoke to her preschool teach and she said she’s been fine. No better or worse than normal at school and she doesn’t have any concerns about her behavior.My one thought is that she spends soo much time bottling up her energy and emotion at school that she just explodes whenever she is home. Which, I get. But I am losing my mind over here and I don’t know what to do. Should I be doing more time outs? Less time outs? Something totally different. ANY advice is appreciated. via /r/Parenting https://ift.tt/2Uc73X6