Computer Extremely Slow From Hibernation/Sleep

Hello,

I have a Dell Inspiron 15 5000 series. When booting up from completely off (battery removed, etc.) everything works fast. Logging in is fast (< 5 seconds), accessing browsers immediately is fast (seconds), etc.

However, when I close my lid and come back to it later it is very slow to log in. Logging in takes up to a minute/minutes, then accessing any browsers is extremely slow and the pages are worse than dial-up.

This issue resolves itself when I do a hard reboot (hold power button down) or physically remove the battery before rebooting again, and it's fast as usual.

What could be happening and please hopefully someone has a solution?

Thanks