I want to display visual/auditory stimuli inside a web browser for psychophysic experiments. I plan on using python, but I am concerned with timing. I obviously can not rely on screen refresh for timing which is common in these types of tasks. How much can I hope for in terms of accuracy for timing on the web and what are the best tools to use with Python. I am thinking of using FastCGI
I just want to hear peoples thoughts on this.
Do your timing in JS, save current time in ms on document.ready and then when user hits a key.
Benchmark your test with either

high-speed camera, or
test rig that "hits" a key, e.g. screen flash -> pohototransistor -> usb device -> virtual keyboard
Achieving best timing online for psychophysics experiments using Python on the web