You could use the word 'turgid'...
inertia
A better word than "slow" could be "lethargic," which conveys a sense of sluggishness and inactivity. Alternatively, "gradual" emphasizes a slow process while suggesting a sense of progression. Depending on context, "plodding" might also work, as it evokes a sense of steady but laborious movement.
The term "doldrums" comes from the Old English word "dol," meaning stupid or foolish. It was originally used by sailors to describe the calm, windless parts of the ocean near the equator that made sailing difficult and slow. Over time, "doldrums" came to signify a state of inactivity, sluggishness, or boredom.
The word family for "lethargy" includes related terms such as "lethargic," which describes a state of sluggishness or lack of energy, and "lethargically," an adverb that describes performing actions in a slow or sluggish manner. Other related words may include "lethargist," referring to someone who exhibits lethargy, and "lethargize," which means to make lethargic or to induce lethargy. These words all share a common root related to the concept of inactivity or fatigue.
Sloth means laziness, sluggishness etc. The word can be used in different situations. It is used specially as a dislike of work or any kind of physical exertion.
genre...?
The volcano has been inactive for many years.
It is inaction, inactivity, inactiveness
the state of equilibrium or inactivity caused by opposing equal forces
The likely word is hibernation (extreme winter inactivity).
The root word "hibern" is derived from the Latin word "hibernare," which means to spend the winter. It is commonly used in words related to hibernation, which is a state of inactivity and metabolic depression in animals during the winter months.
Try 'idleness'.