A trick that can also help: the removal of " useless " constraints or more news.
For example, a part that you would have removed from your assembly but whose constraint remains unresolved (but why on earth does Solidworks do that?)
Macro Identification and Removal of Faulted Constraints - Macro - myCAD Forum
I would even say in the case of unnecessary constraints, remove parallelism constraints in sketches as well as in assemblies when possible. Or find another way to coerce.
Parallelism is often redundant with other constraints or dimensions.
Do a test, go into a sketch, enable the sketch feature " Show/Delete Relationships " and as soon as you see parallelism, delete them. If the sketch is not constrained, add a constraint of the collinearity type or a dimension or direction. You're going to delete a lot of them.
It is important to know that constraints form loops that suppress degrees of freedom and often orientation constraints are redundant to positioning constraints. You have two constraints instead of one. And when your sketch is large or many constraints accumulate, SolidWorks gives you a sketch on constraint for no reason. Well, yes, but it's hard to control!
In assemblies it is different as said @coin37coin, the constraints that have not been removed are due to the dialog box which asks you beforehand if you want to delete the elements linked to a part that you are clearing. If this box has been unchecked, then next time it will keep the constraints and put them in a delete state.
The skeleton principle eliminates 2 thirds of the constraints of an assembly, except for the screws
But that doesn't take away from the fact that you have a high-performance PC on SW
I don't know about you, but I have the strange impression that @FRED78 has a lot of skeletons in his closet! 