I have the same problem as you and there is no magic solution, Solidworks is to be thrown in the trash. I have a 600 MB IGES representation of a structure. Import on Catia V5 less than 5 minutes (I didn't count its going fast lol). I tried on FreeCad it opened it to me in about 20 minutes and its running in addition and Solidworks even 4 hours after nothing (( the most frustrating thing is that there is not even a percentage or estimate of the time remaining just a bar competes with Processing of entities in progress.... It's not the first time and it's really disappointing.