I am playing through BG1 with BGT, and I have a minor gripe and wondering if anyone can steer me towards a solution.

I am not sure if this is a normal issue, or one introduced by the patching/modding/bgt. Khalid seems to walk about twice as fast as everyone else in my party. This leads to lost of click and wait, as well as lots of Khalid getting ambushed before the party catches up.

Anyone know if this movement speed difference is normal? If so, why? Do some races move faster than others?

It isn't supposed to be that way. I've installed BGT many times and Khalid always had normal movement speed. There are mods that switch around the classes and kits of BG1 NPCs, perhaps you have one of those installed? Check Khalid's in-game character sheet and see if he's been changed to barbarian, as barbarians move faster than other characters.

If you've got something like shadowkeeper then you can adjust the movement speed of the characters - maybe check to see if Khalid's got a much higher movement speed and then drop it back down.

For my current game it was either Xzar getting ahead of everyone - just what I needed, a mage running into melee LOL.
I figured it was just that he wasn't weighed down with armour or something.

I had the same problem myself, ages ago. I think it was because I'd installed a mod that changed walking speeds to try to make BG1 Tutu better emulate the original BG.

I was able to fix the problem using sword coast keeper, a saved game editor.

http://swordcoastkeeper.chez-alice.fr/

Go to the afflicted character and go to the affects tab. I did a google, and the effect you need to remove is given by

Type = 0x00B0
Param1 = -3
Param2 = 0
Time = 0
Flags = 0x00000009
Target = 0x0001

http://forums.gibberlings3.net/index.php?showtopic=13160

Yeah normal walking speed in BG2 is 9 units. Normal walking speed in BG1 is 6 or 7, which is painfully slow especially if you played BG2 first. Wearing the Boots of Speed sets your speed to 11, which is not only the same normal speed as a barbarian in BG2, but also the max walking speed the engine will allow for the first game.

If you're using Shadowkeeper, though, it displays the walking speed as 0 if you're at normal speed and everything else as a modifier. Normally, that 0 in Shadowkeeper means 9 units, but different character models have different base speeds. For instance, the shadow thief model moves MUCH faster than a standard character at its normal base speed. So just make sure everyone's at 0 unless they're using a non-standard model.