We are looking to measure the length of time it takes for certain key pathways to become 'usable' e.g. certain styling elements will have loaded in and some information ajaxed in on a page. Ideally this could be automated as we currently monitor load times in browser in a manual fashion.
The amount of load is not of primary importance in these tests.
I have written JMeter tests for load, but JMeter does not natively measure the time it takes for ajax requests etc. I have also looked at Gatling briefly, but am unfamiliar with scala.
I am aware of the JMeter WebDriver plugin, but have also heard that selenium is not good for these kind of tests, as it can add load to the server itself, skewing results.