Resolve is pretty brutal on hardware - far worse than premiere.
Firstly though, regarding your 265 footage - are you creating optimised media which should make it nice and easy to use even on your setup.
In addition, set the timeline to a lower resolution, do all your edits there, there just bump it back up to your desired output pre-render.
Ive used a very similar laptop setup acceptably within limits for editing 4k/60 from the drones for a while.
Fusion is going to add a new layer of hardware hurt though.
Things using temporal filters such as noise reduction etc will murder it.
Ultimately what Resolve wants is a GPU with a decent amount of VRAM to handle it properly. Also 32gb of actual ram.
Sadly everything there is holding you back, Resolve uses CPU for some things, others need GPU (see above).
Mechanical drives are a serious bottleneck in any computer system these days.
FWIW my old Dell with i7/8th gen with Geforce 1050 Ti / 32gb ram and SSDs worked fine on resolve as long as i didnt use noise reduction or much Fusion. If i did, it crashed.
My newer laptop is a 13th gen i9/Nvidia 4070/32gb/SSDs and its far better.
But a desktop is a lot more economical to build from scratch. Sadly with your setup i suspect its a new motherboard and new everything to plug into it. That ISNT too costly though for a desktop.