Sony xperia z1 compact problem copying from internal memory to pc topic

hello there i have bought my foirst sony phone and tbh i loved the htc way better as i like fast small phones and htc ones were getting 2 big for me.well im running into this problem with moving movies from showbox which is on my internal memory to my pc when i connnect the sony to my pc and try to copy movies it takes a while as it says something is in use but when i highlight what i want to move and leave it for about a minute then i can move it why is this so slow and well i hate that sony has it this way.would you guys have any idea of what im going wrong tbh would rooting solve this problem.also i dont see many custom roms out there for this device.i dont mind the stock rom its use i cant move sertin apps to sd card which is a pain and will rooting solve this problem.i would love a clean fast custon rom for this phone which has no bugs or problems and no crapware sony has on my phone.