>>>>What I decided to do (and suggested to the customer) as a test, is to move the application .EXE to the PC local drive. Hopefully this will show if the app starts faster and works faster; which will point to something (probably AV) slowing down the data access.
>>>>Thank you.
>>>
>>>If the app runs faster on a local machine then yes, something in the network environment is slowing down the networked version. But there are many possible causes, not just AV. If you say "it's probably AV" but it actually isn't you'll lose credibility. I'd just tell them it's something in the networked environment, and get their IT support to solve the issue.
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>>I moved the app to the local drive and it is considerably faster. There are two users from different PCs and both experience the problem. I asked them to shut down Windows 10 Defender, on one PC, and it didn't improve the speed.
>>Now IT is doing some testing of the network. I think the last I have heard is the IT is testing something (I simply forgot the term, not Pinging but another term). It shows that the call from PC to the server goes though some many "servers" or switches. Anyway, they are finally agreeing to test their end instead of blaming the app. The app actually has been working without changes and without problems for a long time. The problem started at the start of the year (approximately).
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>Probably TraceRoute (Tracert). Glad you convinced their IT to look into it.
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>I ran into one case where a network had grown rapidly and had more devices on it than available addresses in the DHCP pool. Normally this would result in a client device not being able to connect to the network, with obvious errors. However, a rogue network segment had been installed and connected to the main one via a static route. There was also a DHCP server on the rogue network. Because of the static route, machines on the main network could get an IP from the rogue DHCP server. They were getting IPs that were not on the main LAN, so all their traffic even to the servers on the main LAN had to go out to the rogue LAN and then back again, through a cheap consumer grade router. Its routing performance was so low that users were seeing only a few percent of their nominal gigabit wired network speed.
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>I widened the main DHCP scope and removed the rogue LAN - all was back to normal.

I wish I knew as mush as you do.