1. I have read that full nodes run all the contracts(several thousands) to verify them so aren't they using too much energy (and also thus spending money) to verify each and every contract that is requested on the network.
2. Since there are too many contracts and also requests coming for them can it be the case that request for a contract take minutes or hours to be performed by the mining nodes?

Sorry for asking such basic questions actually I am new to this stuff.