LoadViz

Runs in the macOS menu bar.

Flames from the bottom show user load. Clouds descending from the top show system load. The most loaded cores show in the middle.

So if the flames are high in the middle it means that one / a few cores are maxed out. If the clouds are sort of low everywhere it means that all cores are having system load.

System and User CPU load are measured for each logical core of the system. RAM pressure has to be inferred:

• If the user part is high on one CPU, getting CPUs with better single core performance might help.
• If the user part is high on lots of CPUs, getting more cores might help.
• If the system part of the CPU load is high, this can mean that your system is swapping, and that getting more RAM might help.