Check the Apple System Profiler for the details. It should give you some more details on the speed of both the RAM and SSD (SSD will be under NVMExpress). I don't currently have access to an Intel Mac to confirm (Apple Silicon Macs have no speed details in those locations, but that doesn't surprise me since they also don't report the same details for other items as an Intel Mac reports).
FYI, SSD write speeds can easily be half of their rated speeds because writes tend to be slower than reads, but it varies due to a lot of factors. I believe a MBPro 2019 SSD would have speeds around 2,000-3,000 MB/s (a 2017 model showed about 1,600 MB/s). I'm sure there are reviews out there which will show the information you are looking for.
As others have mentioned, performance in a VM is always going to be much slower than running on bare metal. The amount of memory the host OS has is just as important as the memory assigned to the guest OS in the VM. Plus all apps & processes running on the host OS will affect performance of any guest OS in a VM (and the other way as well). If your Windows app requires GPU hardware acceleration, this can be another impact on performance depending on how the VM handles access to the GPU.
Memory & SSD speed is probably not going to be the cause of the problem. The amount of memory available to both host & guest OS will have the biggest impact in performance. Also having sufficient Free storage available for both the host & guest OS is also critical, but no different than when running them individually on bare metal except the VM itself may use a bit more resources on the host side (aka Mac side here).
You should also consider the apps & processes you have running on the macOS host. You may need to close down some apps. If you are running any anti-virus apps, cleaning/optimizer apps, or third party security software, then those are easily a problem even without trying to run another OS in a VM.
On the Mac side, you can easily check whether you have enough memory available for macOS itself by using Activity Monitor. Check the memory pressure graph. If it is showing yellow or red, then you don't have enough memory for that workload. Even if the memory pressure graph is green, check the "Swap Used" and "Compressed" memory. If either of these are in the GBs, then you may not have sufficient memory for that workload as well.
On the Windows side, do the same with the Windows memory monitoring tools.
What are the system requirements for the Windows app you are trying to run?