Try and clear the system cache. I know you said you're not tech savvy but this takes 2 mins and might look scary but you won't lose any files or settings or a thing like that. You can always look on YouTube at someone performing it if your really unsure.
So you firstly connect your tablet to a PC/laptop via a USB cable. Then on the tablet scroll down from the top of the screen twice and hit the power button then power off. Wait for the tablet to be fully off and showing the battery percent circle, then hold the power button and volume up buttons simultaneously for 5 to 10 seconds then let go and a blue screen should show up with options. You use the volume down key to move down (and volume up for up). Press the volume down key until you are on "clear system cache". Then press the power button to select. You will come to a screen where you need to confirm your choice by hitting volume down key to the yes option then hitting the power button to confirm.
This will take you back to the blue screen where you should be over the restart device option by default, so then just hit the power button again to confirm you wish to restart and your tablet will reboot.
Also I always use Samsung's "Good Guardians" app and use Galaxy App Booster after an update.
Same happened with me initially on my S8 Ultra but after those steps and a soft reset (hold power button and volume down button until the screen turns off and reboots) and now everything works pretty much perfect