Posts from 100% CPU usage in windowed mode.

http://imasters.org.ru/viewtopic.php?id=41

a tool for fixing bugs in Heroes of Might and Magic I, II, and III.

created a similar one for Heroes 2 PoL 2.1 under Windows, in English.
http://ifolder.ru/15739493

In full-screen mode, the CPU usage is also at 100%. You can clearly hear it from the fan noise :)

A patch is needed. I wrote my own. I didn't like the others because they create an entire additional section just to insert:

push 1
call ds:Sleep

And, of course, a jump there and a jump back. It's possible to do without an additional section and without jumps.

Does anyone know how to patch an .exe file in more detail? (I need to do this to merge it with existing patches. I used to work with SoftICE and IDA Pro, so I think I could do it myself if someone could give me a more specific direction.)

Principle. Before - after.
.004855E0: 55 push ebp
.004855E1: 8BEC mov ebp,esp
.004855E3: 83EC20 sub esp,020 ;' '
.004855E6: 53 push ebx
.004855E7: 56 push esi
.004855E8: 57 push edi
.004855E9: 6A01 2push 1
.004855EB: 6A00 push 0
.004855ED: 6A00 push 0
.004855EF: 6A00 push 0
.004855F1: 8D45E0 lea eax,[ebp][-020]
.004855F4: 50 push eax
.004855F5: FF15D0965300 call PeekMessageA
.004855FB: 85C0 test eax,eax
.004855FD: 0F8419000000 jz .00048561C --1
.00485603: 8D45E0 lea eax,[ebp][-020]
.00485606: 50 push eax
.00485607: FF15CC965300 call TranslateMessage
.0048560D: 8D45E0 lea eax,[ebp][-020]
.00485610: 50 push eax
.00485611: FF15C8965300 call DispatchMessageA
.00485617: E9CDFFFFFF jmp .0004855E9 --2
.0048561C: E84F080000 1call .000485E70 --3
.00485621: 8945FC mov [ebp][-4],eax
.00485624: 8B45FC mov eax,[ebp][-4]
.00485627: 2B05AC375100 sub eax,[0005137AC] --4
.0048562D: 83F814 cmp eax,014
.00485630: 0F8E20000000 jle .000485656 --5
.00485636: 8B45FC mov eax,[ebp][-4]
.00485639: A3AC375100 mov [0005137AC],eax --4
.0048563E: 833D243F520000 cmp d,[000523F24],0
.00485645: 0F850B000000 jnz .000485656 --5
.0048564B: 8B0DA8405200 mov ecx,[0005240A8]
.00485651: E83AEFF7FF call .000404590 --6
.00485656: 8B45FC 5mov eax,[ebp][-4]
.00485659: 2B05A8375100 sub eax,[0005137A8] --7
.0048565F: 3D96000000 cmp eax,000000096 ;' Ц'
.00485664: 0F8E34000000 jle .00048569E --8
.0048566A: 8B45FC mov eax,[ebp][-4]
.0048566D: A3A8375100 mov [0005137A8],eax --7
.00485672: 6A00 push 0
.00485674: 6A00 push 0
.00485676: 6A00 push 0
.00485678: 8D45E0 lea eax,[ebp][-020]
.0048567B: 50 push eax
.0048567C: FF15F4965300 call GetMessageA
.00485682: 85C0 test eax,eax
.00485684: 0F8414000000 jz .00048569E --8
.0048568A: 8D45E0 lea eax,[ebp][-020]
.0048568D: 50 push eax
.0048568E: FF15CC965300 call TranslateMessage
.00485694: 8D45E0 lea eax,[ebp][-020]
.00485697: 50 push eax
.00485698: FF15C8965300 call DispatchMessageA
.0048569E: E900000000 8jmp .0004856A3 --9
.004856A3: 5F 9pop edi
.004856A4: 5E pop esi
.004856A5: 5B pop ebx
.004856A6: C9 leave
.004856A7: C3 retn ; -^-^-^-^-^-^-^-^-^-^-^-^-^-^-
.004856A8: CC int 3
.004856A9: CC int 3
.004856AA: CC int 3
.004856AB: CC int 3
.004856AC: CC int 3
.004856AD: CC int 3
.004856AE: CC int 3
.004856AF: CC int 3
.004856B0: 55 push ebp

.004855E0: 55 push ebp
.004855E1: 8BEC mov ebp,esp
.004855E3: 83EC20 sub esp,020 ;' '
.004855E6: 53 push ebx
.004855E7: 56 push esi
.004855E8: 57 push edi
.004855E9: 6A01 2push 1
.004855EB: 6A00 push 0
.004855ED: 6A00 push 0
.004855EF: 6A00 push 0
.004855F1: 8D45E0 lea eax,[ebp][-020]
.004855F4: 50 push eax
.004855F5: FF15D0965300 call PeekMessageA
.004855FB: 85C0 test eax,eax
.004855FD: 0F8419000000 jz .00048561C --1
.00485603: 8D45E0 lea eax,[ebp][-020]
.00485606: 50 push eax
.00485607: FF15CC965300 call TranslateMessage
.0048560D: 8D45E0 lea eax,[ebp][-020]
.00485610: 50 push eax
.00485611: FF15C8965300 call DispatchMessageA
.00485617: E9CDFFFFFF jmp .0004855E9 --2
.0048561C: E84F080000 1call .000485E70 --3
.00485621: 8945FC mov [ebp][-4],eax
.00485624: 8B45FC mov eax,[ebp][-4]
.00485627: 2B05AC375100 sub eax,[0005137AC] --4
.0048562D: 83F814 cmp eax,014
.00485630: 0F8E20000000 jle .000485656 --5
.00485636: 8B45FC mov eax,[ebp][-4]
.00485639: A3AC375100 mov [0005137AC],eax --4
.0048563E: 833D243F520000 cmp d,[000523F24],0
.00485645: 0F850B000000 jnz .000485656 --5
.0048564B: 8B0DA8405200 mov ecx,[0005240A8]
.00485651: E83AEFF7FF call .000404590 --6
.00485656: 8B45FC 5mov eax,[ebp][-4]
.00485659: 2B05A8375100 sub eax,[0005137A8] --7
.0048565F: 3D96000000 cmp eax,000000096 ;' Ц'
.00485664: 0F8E34000000 jle .00048569E --8
.0048566A: 8B45FC mov eax,[ebp][-4]
.0048566D: A3A8375100 mov [0005137A8],eax --7
.00485672: 6A00 push 0
.00485674: 6A00 push 0
.00485676: 6A00 push 0
.00485678: 8D45E0 lea eax,[ebp][-020]
.0048567B: 50 push eax
.0048567C: FF15F4965300 call GetMessageA
.00485682: 85C0 test eax,eax
.00485684: 0F8414000000 jz .00048569E --8
.0048568A: 8D45E0 lea eax,[ebp][-020]
.0048568D: 50 push eax
.0048568E: FF15CC965300 call TranslateMessage
.00485694: 8D45E0 lea eax,[ebp][-020]
.00485697: 50 push eax
.00485698: FF15C8965300 call DispatchMessageA
.0048569E: E900000000 8jmp .0004856A3 --9
.004856A3: 5F 9pop edi
.004856A4: 5E pop esi
.004856A5: 5B pop ebx
.004856A6: C9 leave

Changes started here:

.004856A7: 6A01 push 1
.004856A9: FF15E8955300 call Sleep

Restore the overwritten ret:
.004856AF: C3 retn ; -^-^-^-^-^-^-^-^-^-^-^-^-^-^-
Another function:
.004856B0: 55 push ebp