In the tech support forum they said to post here if you were willing to run benchmarks. I'd be glad to try.

Rusty is working on Wesbench. The idea is to create a set of scenarios, each of which tests a seperate thing. There are three already made. Here are some more of his ideas:

fog reveal: moving units through fog
complex WML parsing
scroll tests over different domains (esp. owned villages with waving flags)
lots of units for AI to analyze

Save these files to: wesnoth\data\scenarios\multiplayer
Read the description tag in each file for instructions on running it from the command-line.