I would just like to say im having the same issue so its no faults with your computer!, i swapped my game from my HDD to my SSD, the full second freezes turned into .5s freezes, still there and still annoying but yea, cl_loadmodelsondemand never helped, and it seems to have transitioned to other source mods aswell (i'm a previous developer of a mod and this issue has transitioned over to that mod aswell, which is really goddamn annoying as these are the only two games i really play)

Here is hoping valve fixes this soon :)