You could be running out of memory, make sure you aren't using more characters than your system can handle. Open the task manager before pressing go out and check how much memory the game is consuming.
Some characters are heavily modded and steal a lot of memory when preloading the game. If this is the reason you can disable specific plugins like the ForceHighPoly that are extremely unoptimized and forces the game to load all character assets into the open world, this will make modded characters look uglier when walking around but could fix the issue.
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