I always think the Core 2 Duo was the inflexion point for me. Before that current software always seemed to struggle on current hardware but after it was generally fine.

As much as I like my Apple Silicon Mac I could do everything I need to on 2008 hardware.

Alongside the power of a single core, that was alongside adoption of multicore and moving from 32 to 64 bit for the general user, which enabled greater than 4GB memory and lots of processes to co-exist more gracefully.