Compile time has many factors, CPU use, RAM use, and the scale of the changes are the three chief ones. Compile times should remain much lower than 15 minutes for a fresh project.
Is your project a mix of C++ and BP or just C++?
If both, does standard BP compile take as long?
Here’s another thread users were discussing the differences in comp times/speed from UE4 to 5, might not provide much but a bit of extra insight: