I see cache changes every 2-3 days for my sites therefore you should know by Monday/Tuesday if it has made any difference.

FWIW the experimental changes I have made moved some pages straight back onto the first page and some have steadily climbed upwards a place or two with every cache change.

Is this the only alteration you made?

> Does anyone know how soon Google recognizes the changes?

Guess it depends on the changes you make. I added noindex meta tags to some of my pages about three months ago, they're still there.

I made a few other changes, such as - I had a leader board at the top of the page with a 336x280 underneath it. I moved the 336 to a right hand column, but placed it underneath a VSW 336 ad. There is only one ad between my head section and the content now.

I haven't heard anything about H1 tags helping with Panda issues, I'm afraid. But if it makes for a better site, that part's good.

As far as crawling - if you're in GWT, you could go in there and take a look at the crawling rate, to get some idea of how often they are crawling and indexing you now.

If your traffic has slowed way down, it might be that it takes a little longer to get crawled again. I notice that on my seasonal sites, the busier they are, the deeper and faster Google crawls them, and then when I'm off season, the crawl slows way down too.

Also I launched a couple sites over Memorial Day weekend, and we messed up on the url structure on one of them - and even though we fixed it within 48 hours, it's taking forever to get it thoroughly crawled and indexed. The other one (which was virtually the same except targeted to a different location) popped right in and was ranking and bringing traffic immediately. I think we shot ourselves in the foot with the url mistakes.

Netmeg, the reason I believe H1 tags had a huge part was that, for example, in one folder with perhaps 300 documents, the H1 tag was the same for all those documents which would indicate duplicate content. I changed all the H1 tags to represent the main topic of the page. I may be wrong, but after investigating all the possible reasons, this is the one that seemed to make the most sense to me.

BTW, today is really BAD!