I think - when were talking about MM specifically - it's not so much the reading/writing of data that takes so much time (maybe it's worse with classical HDDs, but I wouldn't know because I have NVMe SSD) and causing a delay, but rather the single "threadedness" of the game, and that data (it's tens of thousands of entries MM has saved up) simply cannot be processed quickly enough due to not enough CPU being available for the task.
Looking at eso64.exe in Process Explorer, there's just one thread that uses most of CPU time, so unfortunately it seems like not even the LUA system can run its own instance of sort
I really hope there will be Vulkan renderer coming in this year, because that would most probably solve all these problems. The way I understand it, the problem is DirectX11.