The impact on speed depends heavily on the (size of) data and the functions one uses. When applying advanced algorithms like a Fourier transformation on medium sized data, the CPU can be main limiting factor.
If on the other hand someone performs rather elementary calculations on large datasets, the amount of memory available can slow down the computation. The memory limits can be adjusted under the System Settings tab from the Tools > Options… menu. The useable memory is limited to 2 gigabytes for the current releases, but the upcoming 64-bit-version will go beyond this size.
When using huge datasets that don’t fit in the memory, the main impact is the speed of the hard drive where FlexPro’s temporary file folder is located. Results of calculations are written to and read from files in this directory. One can change the location of this folder in the System Settings tab.