If you want to find out average load times for eg how long nodes take to load use the following iis log query and then filter the data in excel:
cs-uri-stem AS URI,
FROM 'C:\###FOLDER TO LOG FILES###\*'
WHERE cs-method = 'POST' and (
/*loading a node*/
cs-uri-stem like '%Content-Editor%' or
/*loading children of a node*/
cs-uri-stem like '%execute.aspx%'
/*opening languages for a node*/
cs-uri-query like '%Gallery.Languages%'
ORDER BY time-taken DESC
See IIS Log parser for how to run these queries.