To suggest you or somebody to upgare one's PC is quite subjective opinion I believe. Because the end user and who is paying for is not the person who is suggesting :).
Anyhow there are a few points to consider here to speed up the simulation process before investing in hardware components or upgrading your PC.
(1) Check what solver you are using.
(2) Check if your selected solver in your model is a fixed step or variable step size
(3) Check the possibility of employing Parallel Toolbox functions
(4) Check your MATLAB's memory management
(5) Check MATLAB's concurrency and if possible take the max number of available cores
(6) Check if your model uses any functions from external libraries
(7) Upgrade your MATLAB license to the latest version, e.g., MATLAB 2023b is much faster than MATLAB 2017a
(8) Use Profiliung to optimize your model to find out where your model spends most time.
If you still want to invest in your PC upgrade, then consider these points:
(1) Upgrade CPU. MATLAB simulations are bound to CPU. If possible, consider a multi-core CPU.
(2) Upgrade RAM. It helps faster and easier to handle datasets from your models.
(3) Upgrade GPU. MATLAB now supports GPU based computations.
(4) Upgrade or switch to SSD for data storage. SSD speeds up data writing and reading.
That is all.
