Macbook Pro 16 2019 i9 is slow

Hello,

So I am struggling now as I cant find any help on the internet. I got MB Pro 16 2019 with i9 processor, 32gb of Ram and AMD 5500M 4gb

The problem that it works slow when I try to do some photo edditing, especially export or recently for example video editting in Premiere Pro. So firstly the problem is whenever I go for example to safary to find some picture to add in to project when I come back in Premiere Pro I need to wait 5 seconds as Premiere Pro doesnt respond and if I press Play its starts playback after few seconds wich is very annoying. I am editting 4k video from Sony A7III but in a 1080p project. Another thing al systems becomes very slow when I decide to render my project, but I checked that the load on aprocessor isnt full so I don't understand why computer beggins to lag

I use my Macbook Pro with external 2k monitor Dell U2722DE and the laptop is closed, so only using one screen

Could please someone help me with this performance issue, as it should be capable machine, but it struggles with basic work tasks