Your best case scenario is to have only one switch between the client machines and the server. The more switches you put between them the slower SolidWorks will perform when accessing files across your network. So, regardless of the rest of your network architecture you will want to limit the switches you pass through for the purposes of using SolidWorks.
Ultimately, as fast as a Gigabit Ethernet is, that setup will still be notably slower than local storage or a PDM system that caches files off the network into local storage. This is a write-up from a few years back but is still very relevant to use of network storage today (Working Across the Network vs. Working Locally). Since that article was written though PDM Standard was released and comes included with SolidWorks Professional and Premium licenses. If you have these licenses then you have already bought a PDM system. You would just need to plug it in and turn it on.
Unfortunately, there is no amount of time or effort that could be put into the architecture of your network that will surmount the issues you will face.