are spider cracks something to worry about?

Depends on whats causing them. If its just in the gel then its only cosmetic and you can decide if you want to live with it our not.....if they go through the glass then there maybe sturctural issues at play.
Where are they located? How big are they and whats behind them?

the corners of the windshield and the back where the bench and side connect to close off the engine compartment

cosmetic

ok good... so i dont have to worry about running it hard in big waves... its a solid boat but its 87 scarab panther so it is an older one..

I wouldn't worry about it. Always a good idea to inspect the bulkheads after running it hard in rough water. Even apache's can knock a bulkhead loose.

Try asking Fountain owners . They would all have first hand knowledge .

Every 30' Scarab that I looked at back when I was looking at that boat had them, and all of them had the cracks at the base of the windshield