You can opt for WorkSpaces Manager to automatically change compute type of a WorkSpace. This is useful if, for example, you had a user running heavy spreadsheets on a Standard WorkSpace and it would benefit them with being upgraded to a Performance WorkSpace. This will also downgrade the WorkSpace if it has been over provisioned for a users day to day needs.
Set Low and High Processor and Memory values (these are up to you). WorkSpaces Manager will also advise you of recommendations.
It will also advise the user in their portal if an optimization recommendation is required. They can either schedule it there and then, or can schedule it at another time (i.e., when they are not working).