Performance and Capacity

ATL-CSIM: System Simulation and Modeling Tools.
Lockheed Advanced Technology Labs' CSIM is a general purpose discrete-event simulator for block diagram oriented systems. Graphical/interactive or text/batch simulations. Not to be confused with Mesquite Software's CSIM18, another simulation tool.
http://www.atl.external.lmco.com/projects/csim/

Internet Speed Boost Solutions
Modem tweaks and browser tips to speed up Internet access. Reports web accelerator software options which claim full optimization.
http://www.inboost.com/

Quantitative System Performance
Introductory text on analytic computer performance models. Complete text is available as searchable PDF. Published in 1984.
http://www.cs.washington.edu/homes/lazowska/qsp/

Stratton & English Software - Performance Specialists
Provider of Internet Software Services, specialising in Performance Investigations - including performance prediction, optimisation and testing.
http://www.strattonenglish.co.uk

University Classes on Computer Performance
Web sites for academic classes on computer performance. Typical contents include syllabi, readings, homework, and lecture notes. Useful to students, instructors and practitioners who want to review the basics.
http://www.frontrunnercpc.com/info/classes.htm