Does USB 3 improve latency for audio device?

[AdvancedFollower]

USB 2.0 has a latency of 0.125ms which is neglible in the grand scheme of things. For example with a buffer of 256 samples at 44.1 KHz you're getting 5.8ms of latency and twice that for round-trip latency, so another 0.125ms one way or the other won't really be noticeable. USB3 could in theory get lower than that, but as you can see, the latency of the USB interface itself isn't really a contributing factor.

The most important thing for latency is to disable any throttling/power saving features and make sure your DPC latency is as low as possible, so you can use lower buffer sizes without dropouts. Use Latencymon to find problematic drivers and make sure your video card, LAN/Wi-Fi adapters etc. support Message Signaled Interrupts (usually MSI can be forced via regedit even if it isn't enabled by default).