Most of the increases in save time are a tribute to the sector size.
When sectors were 2,5km boxes, there was a room of X objects to save, with doubling the size, we have round about 4 times the objects in the sectors, and the average station and ship size increased.
Some servers even increased their sector size far beyond that.
So, if we had a former sector size of 2.5km (1.25km from center to each sector marker), you had a loaded area of round about
7.5km x 7.5km x 7.5km (422km³)
With a sector size of 10km for example, you end up with
30km x 30km x 30km (27000km³)
And players usually worship that free space and never build anything in it that would not fit in those smaller sectors.
:P
No, really,
the longer autosaves are usually something on servers with large sectors.
Or limitations in disk-IO by writing large portions to disk, as the optimization that was blamed here, even skips writing anything to disk that was not changed, so if you have a server with those long autosaves, send me a copy of one log that covers an autosave (serverside!) and the servers settings.cfg, will look into them, and check if there is something unusual happening there.
- Andy