Alright, so this is probably a multi-pronged problem, let me try to explain.
- Good job on trying the Disable All Modules, that can definitely help (run through this to get troublemaker modules permanently disabled: Trouble with Modules)
- The Pathfinder 1 and Pathfinder 2e game systems are HUGE. This means those migrations do indeed take a lot of time, which is what you’re seeing. You can open the Dev Console on your browser (Press F12), and click the “Console” tab to watch what it’s doing. It SHOULD be outputting logs there as it works through things (hopefully giving you some indicator as to where it’s at in the process)
- Slimming a world down can definitely help, no doubt about that. Give this FAQ a look to see how you’re sitting for World Size: World Size Check
Overall, this might just be a waiting game, but give those a try, see how it comes out.