The keyboard of my ipad1 is very slow when using safari. I don't have a problem using any other app. What can cause this problem?
Is this slow keyboard behavior when you type in a URL to go to a specific web site, when you type in a search term in Safari's search box or when you are inputting text in an area on the web site itself?
It may very well be your Internet connection and/or the web site text box in which you are typing. Oftentimes, if you are inputting something directly to the web site, your keyboard actions are being transmitted "live" - the iPad/Safari/web site are not waiting for you to finish typing. You're kind of streaming your typing. So, if the Internet connection is not the greatest, or the web site is not set up to do this "streaming" action well, then yes, you will have a typing delay.
If it is happening on only a few sites, I would say that's not something to worry about. If it's happening across all sites - take a look at your upload speed for your Internet connection.
If your slow keyboard effects happen when you are typing an address into Safari's URL or search bar (and then you have to hit return), then that IS a problem with Safari.
Hopefully, that last part is not what you are experiencing. If it is, then do let us know. Otherwise, I'm afraid it's your Internet connection (especially since you state it only happens with Safari).
Hope this helps explain, somewhat. Let us know how you get on.
Marilyn