Hi Ammer
The analysis time depends on the semi-rigid / fully rigid solution, quantities of frame elements, shells and nodes in the project.
with semi-rigid solution, all slabs in system include in analysis as finite elements. So quantities of nodes and elements are much more than fully rigid solution. Saved file size aslo increase.
You can see those information in Analysis Status. See sample picture below.
Please compare this information with different projects, for both semi or full rigid solution.
You may save a file as "Save Compact" to reduce size. Please remember that analysis result will not save with that choice.