yes every usb u add to the same port adds 25ms latency to all
Try using a powered usb hub
Doesnt really make a difference
In theory, yes. Everything downstream from the host is sharing the same bandwidth. So there are periods where the keyboard gets a chance to talk, and periods when the mouse gets a chance to talk.
On a laptop this can be even worse, because there’s sometimes only one genuine USB host and all external ports run off an internal hub.
Most hardened gamers still prefer to use PS/2 ports for mouse and keyboard when they are available. These are interrupt-based, and must be processed whenever they present data, whereas USB devices have to sit and wait until interrogated as to their continued presence and any data they may wish to present.
While I’ve never thought to research it, I’ve always taken it for granted that modern USB keyboards and mouses would be USB2.0, not 1.1.
At USB 2 speeds, I’m inclined to think that the argument about lag is an exercise in splitting hairs. If you think it matters then, in the absence of available PS/2 ports, allocate individual USB ports for keyboard only and mouse only.
I still use PS/2 ports, but that’s because of the age of still serviceable hardware, not because of any technical belief that I have yet to see properly proved.
Further, as a typist, I often encounter keyboard latency even via PS/2 ports. This is because the OS is heavily occupied with some other task and deliberately masks the keyboard interrupt. Depending on how the hardware buffers, this can be 16, 32, or even 64 (very rarely) characters ahead of your computer.
If other software is capturing those keystrokes, I can end up being several sentences ahead of the cursor.