Increase in upload time when scanning large PDF (1GB) with Web Gateway

[mkgurz]

We have the Web Gateway installed on prem that performs file upload scanning in a reverse proxy scenario. We enabled the anti-malware and media type block polices on a test application, however, the user is stating when they upload a 1.3 GB PDF file, the Web Gateway is increasing the file upload time to 75 minutes, compared to 30 when the Web Gateway is not in-line. Is this a normal amount of time for the Web Gateway to scan a file this large? They are asking if the scanning time can be improved or be made more efficient. I have looked through our settings, and we have the amount of client connections set to unlimited, and the amount of AV scanning threads set to 25. We also are only performing Layered Coverage scanning on our anti-malware policy. Not sure where else to look to improve scanning time, or can nothing be done to improve performance since the file being scanned is so large?