[Honor 10 Questions & Answers] StuDB:
Weird, not getting these problems at all, just factory reset and all seems smoother than you're describing.

Have you tried uninstalling pre-installed apps? It's pretty simple to do, the method is detailed here.

I spent some time working out which files I wanted to remove so don't just go with my list as you might want some of them! Also I used "pm disable" instead of uninstall so I can enable them easily enough if I need to.

The one thing I recall made the most noticeable difference was removing the stock launcher, but just a note - this also removes the Huawei iPhone style multitasking and changes it to vanilla android. This was fine for me though as the vanilla is just fine.

Also probably best to install your preferred launcher first and set that to default before removing your stock one. I'm use Lawnchair so I set that up first.. Oh and you can't use gestures with a third-party launcher, but again I'm perfectly happy with my navigation bar.

Hope this helps you out.. If it doesn't work I'd say take your phone back, it shouldn't be that slow!

List I removed:

pm disable-user --user 0 pm disable-user --user 0 com.android.egg

pm disable-user --user 0 com.baidu.input_huawei

pm disable-user --user 0 com.huawei.appmarket

pm disable-user --user 0 com.huawei.android.chr

pm disable-user --user 0 com.huawei.android.FloatTasks

pm disable-user --user 0 com.huawei.stylus.floatmenu

pm disable-user --user 0 com.huawei.android.hwpay

pm disable-user --user 0 com.huawei.wallet

pm disable-user --user 0 com.huawei.android.tips

pm disable-user --user 0 com.huawei.android.karaoke

pm disable-user --user 0 com.huawei.parentcontrol

pm disable-user --user 0 com.huawei.vassistant

pm disable-user --user 0 com.huawei.watch.sync

pm disable-user --user 0 com.huawei.mirror

pm disable-user --user 0 com.huawei.iaware

pm disable-user --user 0 com.huawei.contactscamcard

pm disable-user --user 0 com.huawei.geofence

pm disable-user --user 0 com.hisi.mapcon

pm disable-user --user 0 com.amazon.aa.attribution

pm disable-user --user 0 com.facebook.system

pm disable-user --user 0 com.booking

pm disable-user --user 0 com.facebook.orca

pm disable-user --user 0 com.ebay.mobile

pm disable-user --user 0 com.facebook.katana

pm disable-user --user 0 com.facebook.appmanager

pm disable-user --user 0 com.netflix.mediaclient

pm disable-user --user 0 com.netflix.partner.activation

pm disable-user --user 0 com.huawei.android.launcher

pm disable-user --user 0 com.android.providers.partnerbookmarks

pm disable-user --user 0 com.google.android.marvin.talkback

pm disable-user --user 0 com.google.android.apps.tachyon

pm disable-user --user 0 com.google.android.apps.wellbeing

pm disable-user --user 0 com.google.android.videos

pm disable-user --user 0 com.google.android.music

pm disable-user --user 0 com.huawei.appmarket

pm disable-user --user 0 com.huawei.android.chr

pm disable-user --user 0 com.huawei.android.FloatTasks

pm disable-user --user 0 com.huawei.android.tips

pm disable-user --user 0 com.huawei.parentcontrol

pm disable-user --user 0 com.huawei.vassistant

pm disable-user --user 0 com.huawei.contactscamcard

pm disable-user --user 0 com.swiftkey.swiftkeyconfigurator

pm disable-user --user 0 com.touchtype.swiftkey

pm disable-user --user 0 com.huawei.health

pm disable-user --user 0 com.facebook.appmanager

pm disable-user --user 0 com.facebook.services

pm disable-user --user 0 com.facebook.system

pm disable-user --user 0 com.netflix.partner.activation

pm disable-user --user 0 com.huawei.android.totemweather