Some people like that while others don't. So if you want to get rid of this unnecessary animation (leaving `standard` flip when time really changes) here is the way:
Simply download and install cab file corresponding to your manila version.
Download modified file for your version of manila (see below).
Disable TF3D (or HTC Sense) in Today settings.
Backup file you're gonna overwrite in next step (just in case
Unpack downloaded file to windows directory on your device (replace original).
Enable TF3D in today settings.
If TF3D doesn't start within few seconds, do a softreset.
If TF3D still won't start, restore your original file.
2.1 WVGA: ZIP CAB
2.5 WVGA: ZIP CAB
2.5 VGA: ZIP CAB
stock AT&T Tilt2: ZIP CAB
I'm not a flashing freak, so the only rom i tested it myself is TESS, therefore i cannot guarantee it will work on your device. However i see modified files spreading around forums and many people says it's working.
If you're unlucky and provided file doesn't match your manila, you may still try to patch yours with my online patcher (still experimental)
buy me a shelby gt 350 ;]