So it seems that one of the scripts that are required in Roblox, the name is corescript I believe, are causing an error that make the game freeze for about 20 seconds on startup. I haven't messed around with anything, nor used any models from the marketplace or that I didn't make myself. Here's the error I get:
12:21:09.563 - UiMessage is not a valid member of Frame
12:21:09.564 - Stack Begin
12:21:09.564 - Script 'LoadingScript', Line 525
12:21:09.565 - Stack End
Nothing else in the output and I can't click on the error to open the script.

2 comments
If it's an error thrown by core scripts, your best bet is to go to the devforum and raise awareness to the issue. There's nothing we can do to change that
Ok, Ill see about that. Ill leave the question be for a little in case someone knows whats going on.