I have been having an issue with 2018 when exporting an stl.
Using the same STL resolution settings that I have been using in 2015-16-17 which worked fine now take much longer to export. For instance a 25mb file would normally save in under 5 seconds. Now I can wait 30 to 60 seconds for the same file to export. A file of 200mb or so can take up to 5 minutes to write to disk. I notice the disk is not being accessed except in little fragments every now and then. The computer, OS, and disks are all the same as when 2017 was on the machine.
Solidworks shows 25% CPU usage on a 4 core I7 the whole time it's exporting.
I do notice this is not always true. Sometimes it will export in a "normal" amount of time. Other times it can hang on a 2Mb file for up to 2-3 minutes.