The scanning speed is improved by the cache server component, which is indexing trusted files that could be skipped during scanning. More information about the cache server can be found in this FAQ article.
Certain slowdown of the scanning could be caused by the cache not being fully built yet. In such case, the situation will improve over time (depending on your total hard drive space, but generally the caching should be completely finished in a week while using computer normally).
Also, the issue could be caused by slightly different scan configuration. If you wish to check the advanced scan configuration, please proceed as follows:
1. Open the AVG user interface and press F8.
2. Select Scans -> Whole computer scan (or any other scan you would like to re-configure)
3. Alter the configuration according your needs, or click the Default button to reset it into the default setting.
- Pressing F1 while the scan configuration window is active will display detailed information for this topic.
Besides that, the slower scanning could be caused by having installed more AVG features which were not installed before (AVG self protection was newly introduced with AVG 2013 and could affect the performance) or running more than one resident security application at a time.
Please let us know, if you need to troubleshoot this in more details.