Windows 7: Very long freezes in file system actions, how to trace and debug?

Windows 7 clean install, and file system actions sometimes pausing for ages before going ahead, either just freezing or showing the usual "calculating" message. It's widely discussed on forums, but I can't seem to eliminate it here. It's often across the LAN but happens on the local SSD/HD too. It's often said to happen with huge folders but here it's mostly happening for small operations - creating a shortcut in an empty folder (local/LAN), deleting a folder of 3 items on the local C:\ SSD desktop, or renaming a single file with F2.

PCs are clean Windows 7 x64 install on sandy bridge Asus hardware with >16 GB of 2133 ram, so as far as I can see it's not due to memory/processor/LAN limits.

I've tried possible fixes from numerous forums - antivirus/defender disabled, thumbnail/icon disabled, registry tweaks for non-poooled memory such as LanMan LargeCache=1 and Size=3, disabling NTFS last access/indexing services/linked shortcuts/QoS bandwidth/IPv6, increasing MaxCmds/MaxThreads/MaxCollectionCount to 0x40, disabling {D6277990-4C6A-11CF-8D87-00AA0060F5BF} (remote scheduled tasks related, used to cause slowdown), and had a look at tracer tools like LatencyMon or ProcessMonitor (not sure I am using these as I should, or how to use them for this).

Beyond that I don't understand the underlying causes that can cause this in Windows, and most guides are very vague ("any driver" or "any service" where you have to shut down so much that you can't really test in actual use, and can't tell if it's fixed without using the system for a day or so every change.....) so it's hard to eliminate issues.

Is there a good step-by-step troubleshooting resource on this? I'm not sure where to go next, or how to go about figuring a solution and it's driving me nuts.