Going upwind is tough-much easier on a buggy than on a board. You tend to lose ground on jibes unless you're careful, and the more you angle upwind the more force you need and the slower you go until you're using all your force to stay where you are.
Good equipment is important-the more your kite can generate power at the edges of the window the better upwind performance you'll get. A board with a larger or multiple skegs helps as well for digging harder.
There are also some techniques that help as well: I tend to 'pulse' if I need to gain ground-do S turns or bounce upwind trying to match that with power pulses on the kite. When I'm jibing I try to do it with as little power on the kite as I can get away with, or on a jump.
I think it's just a matter of balancing out forward motion vs upwind, much like on a windsurfer.
I don't windsurf much anymore, though-bad hip.
