improve memory usage

+1 on everything that Bob said.

As long as the "memory pressure" in Activity Monitor stays green, there is nothing to be concerned.

In fact, macOS tries to use as much of the available memory used.

Any application that "frees" or "purges" memory is working against the OS, and not benefitting you in any way.

Davidsdogtraining wrote:

how can i improve memory performance on my imac

What seems to be the problem with "memory performance"?

Do not install third party apps that claim to clean, manage, boost performance, etc. These apps use system resources while providing no benefit, and the may cause problems.

The MacOS manages memory very well.