There are two answers: one generic and one specific to your system.
First, for the general, you need to have an overall understanding of the way the CPU and the associated computer components all work together within the data processing cycle.
Google these words: " CPU data flow diagrams". As you will see there are many ways and viewpoints at varying levels of detail that present components and data flows involved.
Second, for the specific, you need to apply that overall understanding with respect to your CPU specifications plus the specifications for the other components in your computer. The data flows in your system will flow per the diagrams but the technical/performance details within your system determine how fast it all really works. Clock cycles are key. Overclockers speed up their CPUs to process data faster.
Historically adding memory improved system performance. Data did not get bogged down being written and read back and forth on the older mechanical HDDs. Less physical motion was necessay as more data could reside in memory. But older HDD's improved with faster rpms and interfaces. CPU workload was reduced by adding in GPUs - with their own memory. The overall goal to improve performance by speeding up the slowest process in the cycle. Caching, 32 bit to 64 bit. All sorts of hardware improvements leading to things such as the SSD...
If your CPU is only working at 50% capacity and you want to know why then you will need to use some utilities to measure and otherwise monitor your system. Task Manager, Performance Monitor, and a wide range of third party utility programs are available for doing so.
But overall my expectation would be that your CPU is simply more than capable of managing a simple installation and at some point out paces another slower step/component in the process. Could be the SSD or some other factor.