I was wondering if technique such as
Do not scan files that haven’t changed since last scan, scanning only newly created and modified files…etc…
Coz it was recently stated that resources usage and scanning speed can not be improved anymore…
In fact, comparison methods between 'already' scanned not modified [i]and[/i] changed could take more time and resources than to scan it again. You can set your sensitivity to Custom level and disable the scanning (on-access) of open and create/modified files but something [i]in the middle[/i] of this two techniques could be worse... Just thinking loudly ::)I tried to do that. But it seems to ignore that option. I disabled On-Access scan for "open" and left it only active for "create/modify". But it definitly still checks every launched application which really slows down the system. Is this a general bug, a feature to prevent us from disabling it and just giving us the feeling configureability or do I have to change something else than this visible option?
A “launched” application is more than opened - it’s executed. The settings for that are on the first page of Standard Shield settings, not second (and it’s not a good idea to disable them, IMHO).
well, on a clean system a file must be written to be able to be executed (unless it uses some unknown selfextraction), so I dont care about existing files, because they obviously have already been found as not infected.
So will disabling the execution setting still keep on-access scan for written applications?!
It shouldn’t.
Btw, the fact that a file was found not infected doesn’t mean it will always be in the future - it may be a missed file that will be detected only after a virus database update.
So it scans for applications no matter what I set in open/write, but when I disable it it wont scan even when told to scan written files? Or did I misread your answer? 
Well that might be possible, but its rather safe, because if the files remained some time on my PC without hurting it, the chance it will hurt later, when it could have been detected by updated dbs, is low enough for me ^-^. Theoretically it would be enough for me to use the scanner on downloaded files, but neither mozilla/seamonkey nor bittorrent are suppported, so I want to stick to conventional on-write scan :D.
Erm, sorry, seems I misread your question.
Yes, the setting should work as expected - disabling scanning “on-execution” and “on-open” and enabling the scanning of created/modified files should only scan written files, which is what you want.