The glide, typically expressed as glide "ratio" is simply L/D (Lift/Drag), very simple.
So glide ratio is how many meters you fly forward, when you drop one meter (or feet or whatever unit - does not matter).
(Hangtime is a VERY different thing, not happening at max L/D but that was not the question...)
If we take a look at how glide works, without relating to practical issues :
The glide of a kite or any aircraft, is independent of kitesize and rider weight, so constant for a given kite/wing at a specific or optimum AOA, just as Bille wrote
The MAX glide does not happen when the kite is sheeted to max hangtime, but max glide happens at a lower angle - kite depowered a bit
But when the wind comes into play, things changes a lot !
Full scale gliders and model gliders, very often carry water ballast or similar, in order to increase the wing loading (how much weight per wing area).
This is done for two reasons
1. The target for most glider competitions, is to get through turning points very far away and back, as fast as possible.
2. And/or to be able to penetrate heavy headwinds and find thermals/lift far windward.
If you double the weight, you get only half the hangtime, true
But you get twice the forward speed, and the very same glide ratio (speed is directly proportional to wing/kite loading, so if you weigh twice as much, or have half the wing/kite area - you will fly twice as fast, very simple
What does this mean ?
When we jump, we will usually fly with the kite slightly into the wind IMO, during "normal" glides.
And as we often kite in winds over 10m/s, a heavier rider will actually be able to glide further than a light one IMO (or a smaller kite will glide longer than a big one).
If you glide WITH the wind, it changes to the opposite though... The light rider (lowest sink rate) will glide further than the heavy one.
Taken overall, for a glider going out and home - you will always be able to travel the longest distance with the heaviest glider and the same glide ratio, if there is wind, even it you have to go with headwind and tailwind back.
One can calculate on this to confirm if in doubt.
Thus many gliders, carry weight because of this
As the object for "good" pilots, is not to have the lowest sink rate (= max hangtime), but to be able to cover a huge distance to find the maybe sparse thermals around - where you can glide "up" and stay as long as you want - when you are skilled
Of course in kitesurfing - the higher you jump - the longer you can glide, so a too small kite or heavy rider will not give max distance in real life.
Also - there will be more loss when converting energy if too small a kite - so also a difference.
But in general - the stable glide ratio is NOT dependant on kite size nor rider weight, if there is no wind.
Very flat kites, with low drag foils and high AR, will have the best glide, no doubt.
But kites with max L/D profiles will NOT have the best hangtime - as max hangtime requires really deep profiles and drag not as important, whereas max glide happens with faster foils with less drag (and lift)
Hope this gives a very basic idea about how things work regarding glide