Connection slow on certain apps

[AC Question]

Hi. Got a little problem. So I have bought a new phone,stock rom,no root-brand new. Performed all system updates. However, the phone slowly loads youtube videos (once loaded,it plays without stuttering), slowly downloads apps (it stays for a long time with "downloading" message until it starts actually downloading). Also, the apps also logging in slowly. I cant load clash royale,it stucks on updating message. Also,when I log into game Voez with facebook,it takes few minutes to connect with facebook (instead a few seconds). Got any ideas? Performed speedtest on phone, 20mbps in/out. On chrome the browsing speed is fast. That makes me confused.
If I go to google play, it takes time to even load icons. Also i tried factory reset few times ,that didnt help
And I should mention that before doing system updates yesterday clash royale logged in instantly. Maybe the updates is the problem?
The phone is prestigio muze a7, running android 5.1.1

 

[htczed]

As you say the system update you did could have slowed down your phone as sometimes new updates can contain code and or extra features that would slow down your phone as it wasn't specified for by the manufacturer you could try doing a custom rom with us phone as that really helped my S3