Your expectations are high. What apps do you use?
Swiftkey the most
Chrome
Spotify
Bluetooth to my headphones
Those running simultaneously while I'm typing this.
Open one of my current 8 tabs in Chrome, get a memory warning.
Open any game. Memory warning. Some games quit altogether. (dinky toy games)
Eset Mobile Security Premium
Call blocker - 24/7 running
Sticky Password - synced to cloud
DSTV Now
Xcast
ADM
Huawei Router App
WhatsApp/Phone/Text
Gmail (used a lot)
General Apps which include e-learning
Jotterpad
Sleep - alarm clock (without sleep tracking enabled)
Phone has been optimised to the best of my abilities. I have zero lag.
Just unresponsiveness and slowness due to RAM and CPU. I also believe the onboard storage is slow and or low quality. File operations on the internal storage and external storage is very slow. SD Card is slowest though.
Edit: added Eset