@williamp Further to @chiyancheung's suggestion. I've had an issue like this on a desktop computer. I thought I got a Dell 9020 with 16GB RAM. Then when the performance was much less, and I checked I noticed through my control panel it was actually set up by the store who sold it to me, to only use 8GB RAM for the very reason that they set it up for a 32 bit processor instead of 64 bit processor. I was really irritated by this. But maybe this could be your problem too? Your Windows wasn't set up to run as a 64 bit processor, and you have RAM that has not been set up to be used. Perhaps you need to take your laptop to someone who is an expert on setting it up. It's not something I'd like, but in all probability you need to check your BIOS and get it completely up to date with everything. Then after that reinstall your operating system.
I'm not at all an expert, but I know most experts do that when they get a new brand computer or laptop. They completely work their way through BIOS and settings, and reinstall their operating systems. Part of that is to get rid of the advertising junk that the brand loaded on the laptop, and part is to secure it and to make sure they can use all of the specs optimally. The great specs you think you have can only work as well as they have been configured to do.