HoMM3 HD is a mod (add-on) for the game Heroes of Might and Magic 3.

baratorch, can you explain why heroes with the HD mod put the maximum load on the thread in which they run?
I have 4 threads in my processor, and when I run Heroes with the HD mod, the load is 25% - that is, 1 thread at 100%.
Without the HD mod, the load is minimal, 1-2%.

Actually, this is strange because the original game, even without HD, loads one core (thread) to 100%.
The HD mod doesn't change anything here, but if the HD mod uses scaling with some fancy filter (Scale2x, UltraSaI, xBRZ), then the CPU is quite heavily loaded, and rendering uses several cores (threads) - by default, no more than 8 (if your computer has fewer, then the number of cores (threads) of your PC is used). This value can be reduced by tweaking < Graphics.Threads > = ...
but then the rendering speed will decrease.

thank you
it's strange why this tweak even exists. is there any reason to have this value at 0?

Once again: the original game without HD always loads 1 core to 100%.
The tweak < Sys.CPU.ReduceUsage > reduces the load on the CPU (removes these 100% load) by polling input devices less frequently.
This can cause serious lag when using mice with high DPI. Due to such lags, there were even controversial situations in tournament games, so this tweak is disabled by default.