I think, I may be wrong Windows 3.11 was the last Window that provide instantaneous GUI response. Windows 95 was still fast by today's standard but it wasn't "instant".
Windows 3.x did not have preemptive multitasking, apps had to yield in the message loop (cooperative multitasking). This meant that an instantaneous response was possible, but often wasn't, at all. Win95 brought true preemptive multitasking, which was a breath of fresh air.
owlstuffing|5 days ago