BigSur experiences delays when using an iMac from 2014.
BigSur experiences delays when using an iMac from 2014.
macOS Big Sur wasn't built for HDDs. Using an HDD as a boot drive is recommended, but upgrading to an SSD is worthwhile and should be done soon.
It's possible you already have an SSD, but this setup was designed that way, making it unlikely. With only 256 GB available, replacing RAM isn't feasible—you'd need to swap out the logic board, which isn't recommended. Upgrading to an SSD remains the best option. There could also be HDD performance problems or software conflicts, but I still suggest going with the SSD upgrade.