The reason why azab is delayed

If Allah were to hasten evil (i.e., torment) for the (disbelieving) people, as they make haste for the worldly gains, then certainly their term (of life) would have been (hastily) completed for them (so that they reach Hell fast after dying). But We leave those who do not expect to meet Us in their rebellion (and revolt) so that they keep wandering disoriented.

Al yunus 11