I am shocked to report I think found the magic setting to completely resolve the Nvidia latency spikes. It’s easy to set and requires no hacks or third party programs. On my machine, the only side effect is it increases the GPU power usage by 2-4 watts. No problem.
You simply need to run one command at startup to set the GPU’s memory clock to its maximum setting. On my machine, that is 8001Mhz.
You can configure the command to run as administrator on startup. Here is how.
Here is the exact Gearpspace post where I explain the command and some other commands to figure out your supported memory clock. There is some discussion and test results if you feel like reading.
I discovered this by trying the things in this Reddit comment in r/nvidia, where they are tracking the DPC latency issue and offering workarounds. It led me to some person who created a tool to do this, but I soon realized I could do it with a simple command without the tool.
Here is a list of all the other tweaks I did. I am not sure if this Nvidia tweak needs those, but I doubt it. I am still using them, because I think they are good.
If using a Lenovo Legion, then join the Legion Discord and check their knowledge base for lots of good tips. The invite is found in the Legion Reddit. Lenovo Legion Toolkit is particularly helpful.
As usual, use this information at your own risk.