Strange windows floating box

Recently, someone told me that our game will appear on some machines. When a Windows floating box pops up, the game screen will become stuck. At the beginning, I still felt that Mo mingyu was involved. Later, my colleague brought a faulty machine. After testing, I found that ddraw would slow down rendering when a floating box popped up in windows. However, this happens not on all machines, but on some machines. In addition, I also found that when ddraw is tested in dxdiag, most machines will immediately slow down when a floating box is popped up, but some machines will recover immediately, and some will not. At present, I have not found the reason for this. Can anyone who knows the reason tell me.