Correlation between high cpu/ram usage and poor computer performance
There's a general-interest article from the IEEE about transistor aging that's based on the paper "An Array-Based Odometer System for Statistically Significant Circuit Aging Characterization" (2011) by Keane, Zhang, and Kim. They present:


  A system that facilitates efficient statistical aging measurements involving the mechanisms of bias temperature instability (BTI) and hot carrier injection (HCI) stress.


Roberto Lacerda de Orio's dissertation "Electromigration Modeling and Simulation" (2010) has a comprehensive treatment of the physics of electromigration, as well as a numerical model and "several simulation studies of electromigration".

You may find more references in this SuperUser thread.