Is your feature request related to a problem? Please describe.
The replica stats struct is instantiated for different dimensions of load accounting, for a replica. These are contained within replica load:

Every replica has this load accounting. It is desirable to reduce GC'able objects by allocating all replica load accounting memory together and once.

The solution is to migrate the different accounting fields into a single sliding window manager, which would contain all dimensions in each window - rather than maintaining separate window managers for each dimension.

Jira issue: CRDB-19199