The gfx really has no bearing on save times.
Write/read speeds are the only issue or are of concern there.
Your avarage level .usasset is around 1GB, maybe 2.
What’s the write time on that?
You cannot expect the system to go any faster then your write times.
Once you determine that “well, 2GB writes in 10 seconds” then you can start to look into what the issue with the engine could be.
World partition surely doesn’t have anything to do with your run of the mill level…
Look into your timings. Then maybe try a copy of the same uasset in a prior engine version (or a furure one, if one came out its easier to update a copy of the project upawards).