4.1.2 Request Timeout when uploading to

[PSS]

4.1.1 uploads ok (vB attachment upload).
4.1.2: does not upload file (even a small 100kb file which should take 3-5 seconds), instead you get later

"Request Timeout
This request takes too long to process, it is timed out by the server. If it should not be timed out, please contact administrator of this web site to increase 'Connection Timeout'."

Connection timeout is 30 secs, but as I said, upload should have been finished ages earlier. Works ok with 4.1.1 which I reverted to until this is solved.

I do not want to raise timeout.