Wifi incredibly slow after phone sleeps

[AC Question]

I have a galaxy s6 and whenever I connect to my wifi it is extremely fast. After I turn off the screen and let it fall back asleep then wake it back up, the WiFi is still connected and strong, but Web pages and videos on facebook and other apps load very very slow. I can disconnect the WiFi and reconnect and it will be back to being lightning fast, but this is very frustrating and seems unnecessary. I have always network scanning on and network switch off. I have tried dumping the cache through the boot menu and also have forgotten the network and reconnected to it. Does anyone else have this problem and has anyone found a solution? Thank you for your time!