Set Control Panel -> Mouse -> Wheel -> Vertical Scrolling to 3 lines. Restart the PC and don't use TrackPoint scrolling. Check whether touchpad scrolling is more responsive. If it is, please contact Lenovo and demand a fix.

On my T430, with Lenovo-branded Synaptics drivers installed (it's an even greater mess without them), using the TrackPoint for scrolling will reset above setting to 1 line and make touchpad scrolling ridiculously slow. Setting it back to 3 lines won't fix touchpad scrolling until restart.

Worst point: I can't even disable middle button scrolling, so I constantly hit it by accident.

It's ridiculous how PC vendors totally ignore bugs in the most basic functionality. I like where Windows is heading, I like many aspects of ThinkPad hardware (dedicated Home/End/PgUp/PgDn buttons are a huge selling point), but these things are violently pushing me back to Apple.