How to Clean IE Cache with Watir?

we need some sanity test from performance perspective,basically need to get end-end performance result on daily build automatically:

1. end-end response time
2. each page size info
3. clean cache between each test round

so the first item is relative easy to achieve and more straight forward by Watir

for second item, after checking out http://www.newsqa.com/delete-cache-and-cookies-in-ruby/, it works well on Windows XP_SP3+IE6 browser (did not try any other platform)

for the third item, current Iｕｓｅ　"ie.html.length" to get page size, any other better idea? I did not dig this deeper right now.

Or i may consider install a HTTPWatch +Watir to do all the things, haha :)