Adding more memory has no effect unless you are maxing out memory, check task manager.
A bigger power supply would only be necessary should you switch to a new power hungry video card.
Swapping to a faster disk or a SSD would improve performance, but the biggest improvement with a SSD drive would be in boot time and processing of very large files.
Meet the drop-resistant Moto Z2 Force
The Moto Z2 Force is really thin, with a fast processor and great battery life. It can survive drops without shattering.