Re: duration of scanning...
First set the scanning priority to HIGH in the advanced settings of the antivirus/antispyware tab.
Check that other settings are kept at default (e.g. skip files larger than 8MB)
Also disable other security tools while scanning, they may impair the work of the scanner.
Try to avoid to scan compressed file, such as rar files or zip files.
The kaspersky scanner in ZA will open on-the-fly compressed files and scan all elements in it. This may take a long time to perform. Even more if it is a double compressed file since the engine will have to open two compressed files.
You can exclude folders/files under the advanced settings of the antivirus/antispyware tab (scan targets).