Before I dive into the details, I have to make it clear - AVIGen is not usable in its current state.

click to enlarge
You can have the best looking and most feature rich product, but in the case of anti-virus solutions, you absolutely must have up to date virus definitions. Commercial antivirus vendors continuously update their definitions as new viruses are released on a daily basis. Several commercial products offer hourly updates ensuring you’ve got the latest up-to-the minute definitions to protect your computer. Unfortunately, AVIGen hasn’t seen an update in two years, thus making this program nearly useless.
Making things worse, when AVIGen was released in 2008, it only included detection for a paltry 330 viruses. Considering most commercial anti-malware applications can detect and remove over 4,000,000 types of malware, AVIGen can’t be taken seriously.
Since I would very strongly suggest you don’t use AVIGen for protecting your computer, I did not perform any detailed performance tests. The application seems to run fine – scans ran quickly and the user interface worked well.