speed limit ? maybe on WinXP. actually, I was having problems with mouse wheel scrolling with the old "Virtual TreeView" component (used to be standard/grouped view modes).
the current impoementation works a lot faster on Win7 than on WinXP, that I can tell you.
I don't know what could be fixed as the Delphi component used to show games list already have support for mouse wheel scroll. I'll ask the component's author about this.