The processing of certain temp files, certain compressed files and other proprietary files can cause the scan to hang.
This solution will ensure that only files that could contain actual malicious code are scanned.
Large log files, various temporary files and other proprietary program files will be excluded from scanning to decrease the chances of a failed On-demand scan.
Solution
Delete temporary internet files
Slow scan times can be a symptom of uncleared temporary internet files. For instructions to clear the temporary internet files on your computer, see the following Microsoft Knowledgebase article: