>I am going to try this another way.
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>Last time, the issue with loading a Combo Box with 12000 records, caused the whole discussion to be derailed into criticizing the Programming technique of using a Combo box.. So, Lets just forget the Combo-Box altogether.
>
>The problem is, I have ONE customer with seemingly slow network Speed. It effects opening and accessing larger tables across the network that are on the Server (as well as loading Combo boxes, etc). Just doing anything that has to do with accessing files that are across the network seems too slow. But when I access the same files on the Server (accessing data via the local disk) things are lighting fast again.
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>The shop claims to have 1 GIG network gear, but I have customers at other locations running 1GIG network, where the same size tables open 10 to 100 timed faster.
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>So, I am looking for any clues on how to test and optimize the network speed? For example a list of things to look for to optimize the LAN speed?
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>As far as testing goes, I could write a little test PRG that would build a 1 GIG byte file, and then would TIME the transfer (COPY) of this file across the network. In which case, How long should a 1 GIG Byte file take at 1 GIG network speed ?

Most modern networking equipment (NICs and switch ports) have indicator LEDs that show connection speed (e.g. orange for 100Mbit, blue for gigabit). That's one fast, reliable way to tell.

If you're timing a file copy, maximum theoretical throughput for 100MBit is 12.5 megabytes/sec (100/8). There is a little protocol overhead, I don't think it's even possible to reach 12 megabytes/sec under ideal conditions, and real-world performance might be only half of that. If you do a file copy test and you get a number greater than 12.5 megabytes/sec then it has to be a gigabit connection.

If everything seems slow it might be a DNS problem. If DNS is improperly configured, network computers will take much longer to find each other, introducing high latency to all network operations.

If the network has a Windows domain, with a Windows server acting as a domain controller, basically all workstations must be configured to use the Windows domain controller as their sole DNS server.

One common mistake is to configure workstations' DNS servers to be the DNS servers of the company's ISP. Instead, all workstations should set their DNS to be the network domain controller (the local IP address of that server), and a DNS forwarder set up on the domain controller so it can go out to the ISP when necessary to resolve something not in its cache.